text:
Abstract Algebra/Rings

This section builds upon and expands the theory covered in the previous chapter on groups. The reader is strongly advised to master the material presented in the sections up to and including Products and Free Groups before continuing.

Motivation
The standard motivation for the study of rings is as a generalization of the set of integers $$\mathbb{Z}$$ with addition and multiplication, in order to study integer-like structures in a more general and less restrictive setting. However, we will also present the following motivation for the study of rings, based on the theory of Abelian groups.

Let $$G$$ and $$H$$ be Abelian groups. Then the set $$\mathrm{Hom}_{\mathrm{Ab}}(G,H)$$ (Please don't pay much attention to the subscript for now.) of group homomorphisms $$\phi\,:\, G\rightarrow H$$ naturally forms an abelian group in the following way. If $$\phi,\psi\in \mathrm{Hom}_{\mathrm{Ab}}(G,H)$$, define $$(\phi+\psi)(g)=\phi(g)+\psi(g)$$ for all $$g\in G$$. It should be obvious where each addition is taking place. In particular, we can consider the set $$\mathrm{End}_{\mathrm{Ab}}(G)=\mathrm{Hom}_{\mathrm{Ab}}(G,G)$$ of endomorphisms of $$G$$. That is, the set of homomorphisms from $$G$$ to itself. This set is obviously a group from the above discussion, but it is also closed under composition. By endowing the set $$\mathrm{End}_{\mathrm{Ab}}(G)$$ with the operations of addition, $$+$$, and composition, $$\circ$$, we note that it has the following properties:

 * i) It is an Abelian group under addition.

 * ii) It is a monoid under multiplication.

 * iii) Addition distributes over composition.

Indeed, for the third property, note that if $$\phi,\psi,\xi\in\mathrm{End}_{\mathrm{Ab}}(G)$$ and $$g\in G$$, then $$\phi\circ(\psi+\xi)(g)=(\phi\circ\psi+\phi\circ\xi)(g)$$ and $$(\phi+\psi)\circ\xi(g)=(\phi\circ\xi+\psi\circ\xi)(g)$$. The following material is a generalization of this situation.

Introduction to Rings
Definition 1: A ring $$(R,+,\cdot)$$ is a set $$R$$ with two binary operations $$+$$ and $$\cdot$$ that satisfies the following properties:

For all $$a,b,c\in R,$$

 * i) $$(R,+)$$ is an abelian group.

 * ii) $$(R,\cdot)$$ is a monoid.

The definition of ring homomorphism does not include the existence of 1.

 * iii) $$\cdot$$ is distributive over $$+$$:
 * 1) $$a\cdot(b+c)=(a\cdot b)+(a\cdot c)$$
 * 2) $$(a+b)\cdot c=(a\cdot c)+(b\cdot c)$$

We will denote the additive identity in a ring by $$0_R$$ or $$0$$ if the ring is understood. Similarily, we denote the multiplicative identity by $$1_R$$ or $$1$$ when the ring is understood. We'll often use juxtaposition in place of $$\cdot$$, i.e., $$ab\,$$ for $$a\cdot b$$.

Remark 2: Some authors do not require their rings to have a multiplicative identity element. We will call a ring without an idenitity a rng. Pseudo-rings is another term used for rings without unity. Authors who do not require a multiplicative identity usually call a ring a ring with unity. Unless otherwise stated, we will assume that $$0\neq 1$$ in our rings. A major part of noncommutaive ring theory was developed without assuming every ring has an identity element.

Example 3: The reader is already familiar with several examples of rings. For instance $$\mathbb{Z},\mathbb{Q},\mathbb{R}$$ and $$\mathbb{C}$$ with the usual addition and multiplication operations. We have a familiy of finite rings given by the sets $$\mathbb{Z}_n$$ for integer $$n\geq 2$$ with addition and multiplication defined modulo $$n$$. Finally we have an example of a rng given by the sets $$n\mathbb{Z}$$ for integer $$n\geq 2$$ with the usual addition and multiplication. The reader is invited to confirm the ring axioms for these examples.

Let us now prove some very basic properties about rings. This is analogous to what we did for groups when we first introduced them.

Theorem 4: Let $$R$$ be a ring, and let $$a,b,c\in R$$. Then the following are true:
 * 1) If $$a + b = a + c$$, then $$b = c$$.
 * 2) The equation $$a + x = b$$ has a unique solution.
 * 3) $$-(-a) = a$$
 * 4) $$0a = 0$$
 * 5) $$(-a)b = -(ab)$$
 * 6) $$ (-a)(-b) = ab$$

Proof: (1), (2), and (3) all strictly concern addition, and are all previous results from $$(R,+)$$ being a group. The other three parts all concern both addition and multiplication (since 0 and - are additive concepts), so as a proof strategy we expect to use the distributive law in some way to link the two operations. For (4), observe that $$0a + 0a = (0 + 0)a = 0a = 0a + 0$$. But then by (1), 0a=0. For (5), Note that $$(-a)b + ab = (-a + a)b = 0b = 0$$. For (6) note that $$(-a)(-b) + -(ab) = (-a)(-b) + (-a)b = -a(-b + b) = -a0 = 0$$.

Remark 5: Take another look at the examples in Example 3. Notice that for all those rings, multiplication is a commutative opration. However, the axioms say nothing about this. Thus we should expect to find counter-examples to this.

Definition 6: A ring is called commutative if multiplication is commutative.

Example 7: An example of a non-commutative ring is the set $${M}_n(\mathbb{R})$$ of $$n\times n$$ square matrices with real coefficients under standard addition and multiplication of matrices, where $$n\geq 2$$ is an integer. The reader can easily check this for $$n=2$$ and conclude that it holds for all other $$n$$ (why?).

Theorem 8: A ring has a unique multiplicative identity.

Proof: During our brief discussion of monoids earlier, we showed that in any monoid the identity is unique. Since a ring sans addition is a monoid, this applies here.

Example 9: The singleton set $$\{*\}$$ with addition and multiplication defined by $$*+*=*$$ and $$*\cdot *=*$$ is a ring, called the trivial ring or the zero ring. Note that in the trivial ring, $$0=1$$. The reader is invited to show that $$0=1$$ in a ring if and only if it is the trivial ring.

If the reader has tried to construct some of the rings $$=\mathbb{Z}_n$$, he/she may have realised that certain non-zero elements have product zero. We formalize this concept as follows.

Definition 10: Let $$R$$ be a ring and $$a\in R \setminus \{0\}$$. $$a$$ is called a left(resp.right)-zero-divisor if there exists a $$b\in R$$ such that $$ab=0$$ $$(ba=0)$$.

Lemma 11: Let $$R$$ be a ring with $$a\in R$$. Define the function $$\rho_a\,:\, R\rightarrow R$$ given by $$\rho_a(r)=ar$$ for all $$r\in R$$. Then $$\rho_a$$ is injective if and only if $$a$$ is not a left-zero-divisor.

Proof: Assume $$a$$ is not a left-zero-divisor, and assume we have $$ab=\rho_a(b)=\rho_a(c)=ac$$ for some $$b,c\in R$$. This implies $$ab-ac=a(b-c)=0$$, giving $$b=c$$ since $$a$$ is not a left-zero-divisor, so $$\rho_a$$ is injective. Conversely, assume $$a$$ is a left-zero-divisor. Then there exists a $$b\in R$$ such that $$b\neq 0$$ and $$\rho_a(b)=ab=0=a0=\rho_a(0)$$, so $$\rho_a$$ is not injective.

Remark 12: Thus, multiplication by $$a$$ is left-cancellative if and only if $$a$$ is not a zero-divisor. The reader is invited to state and prove the equivalent lemma for right-zero-divisors.

Example 13: $$\mathbb{Z},\mathbb{Q},\mathbb{R},\mathbb{C}$$ are all examples of commutative rings without zero divisors. These rings motivate the next definition.

Definition 14: Let $$R$$ be a commutative ring without zero divisors. Then $$R$$ is called an integral domain.

Just like Definition 14, the majority of special types of rings will be motivated by properties of $$\mathbb{Z}$$.

Example 15:
 * 1) The set $$\mathrm{Hom}_{\mathrm{Set}}(\mathbb{R},\mathbb{R})$$ of functions on $$\mathbb{R}$$ with pointwise addition and multiplication is a ring.
 * 2) More generally, if $$R$$ is a ring, the set $$\mathrm{Hom}_{\mathrm{Set}}(R,R)$$ of functions from $$R$$ to itself is also a ring.
 * 3) The set $$\mathrm{Hom}_{\mathrm{Set}}(R,R)$$ with function composition for multiplication is not a ring since the statement $$f\circ(g+h) = f\circ g + f\circ h$$ is not true in general.
 * 4) The set of integrable functions on the real numbers, $$L^1$$, is a rng under pointwise addition and multiplication given by convolution: $$(f*g)(t) = \int_\mathbb{R} f(\tau)g(t-\tau) d\tau$$. This rng is important to the study of linear systems and differential equations. If the reader has enough calculus under his/her belt, he/she reader is invited to show that it does not have an identity, and that it is commutative.
 * 5) The set of Gaussian integers $$\mathbb{Z}\left[i\right]=\left\{a+bi|a,b\in\mathbb{Z}\right\}$$ with standard addition and multiplication is a ring.

Definition 16: Let $$R$$ be a ring. An element $$a \in R$$ is a unit and is invertible if there is an element $$b \in R$$ such that $$ab=ba = 1$$. The set of all units is denoted by $$R^*$$.

Exercise 17: Prove that $$R^*$$ is a group under multiplication.

Exercise 18:: Show that a zero-divisor is not a unit.

Theorem 19: (Cancellation Law for Integral Domains): Let $$R$$ be an integral domain, and let $$a,b,c\in R$$ be nonzero. Then $$ab = ac$$ if and only if $$b = c$$.

Proof: Evidently $$ab = ac$$ if $$b=c$$. To see the other direction, we rearrange the equality as $$ab - ac = 0$$. But then $$a(b-c) = 0$$. Since $$a$$ is nonzero, and $$R$$ contains no zero divisors, it must be the case that $$b-c = 0$$, which is to say that $$b=c$$.

Definition 20: A ring $$R$$ is a division ring or skew field if all non-zero elements are units, i.e. if it forms a group under multiplication with its nonzero elements.

Definition 21: A field is a commutative division ring. Alternatively, a field $$F$$ is a ring where $$(F - {0},\cdot)$$ is an abelian group under multiplication. As another alternative, a field is an integral domain where all non-zero elements are invertible.

As stated before, integral domains are easy to work with because they are so close to being fields. In fact, the next theorem shows just how close the two are:

Theorem 22: Let $$R$$ be a finite integral domain. Then $$R$$ is a field.

Proof: Let $$a\in R$$ be nonzero and let $$S = \left\{ab| b\in R\right\}$$. Clearly $$S$$ is a subset of $$R$$. From the cancellation law, we can see that $$|S| = |R|$$ (since if two elements $$ab$$ and $$ac$$ are equal, then $$b=c$$). But then $$S=R$$. So then there must be some $$b$$ such that $$ab=1$$. So $$a$$ is a unit.

Of course proving that a set with two operations satisfy all of the ring axioms can be tedious. So, just as we did for groups, we note that if we're considering a subset of something that's already a ring, then our job is easier.

Definition 23: A subring $$S$$ of a ring $$R$$ is a subset of $$R$$ that is also a ring (under the same two operations as for $$R$$) and $$1_S=1_R$$. We denote "$$S$$ is a subring of $$R$$" by $$S\leq R$$. Note many mathematicians do not require rings or subrings to have an identity.

Theorem 24: Let $$S\neq\emptyset$$ be a subset of a ring $$R$$. Then $$S\leq R$$ if and only if for all $$a,b\in S$$,
 * 1) $$a-b\in S$$,
 * 2) $$ab\in S$$,
 * 3) $$1\in S$$.

Example 25:
 * 1) $$\mathbb{Z} \leq \mathbb{Q} \leq \mathbb{R} \leq \mathbb{C}$$.
 * 2) The trivial ring $$\left\{0\right\}$$ is a subring of every ring.
 * 3) The set of Gaussian integers $$\mathbb{Z}\left[i\right]$$ is a subring of the complex numbers $$\mathbb{C}$$.

title: Abstract Algebra/Rings


text:
German/Level I/Introduction

I.0: Introduction

Welcome to Level I German!

Level I is aimed at junior high and high school students. However, it can also be used by others just beginning to learn to speak or read German.

The goal of Level I German is to introduce the basics of the German language without overwhelming students. Therefore, the vocabulary is formatted for translating from English (which the students know) into German.

Although Level II is aimed at students and people who are a bit proficient after Level I, still, English translation will be used, so as to ease the learning. It helps because, at times while learning a new language, even with basic understanding, the words are above normal understanding level, and thus require a "sub" assistance.

German and English
German and English are quite close to each other, and are called language sisters or, more formally, cognate languages. Both belong to the Germanic branch of the Indo-European language family. Here are some major similarities:
 * Both languages use the Latin alphabet.
 * Normally, sentences follow Subject-Verb-Object order.
 * Questions have Verb-Subject-Object order or Adverb-Verb-Subject-Object order.
 * There are contractions (e.g., isn't) in both German and English.
 * Many words share the same roots, such as word and Wort, or house and Haus.
 * Many words are spelled almost the same way in English and German; for example, Text, Zoo, Handball, Motor, Bus, Park, Position, or Garage.
 * Kindergarten (early school grade) is an English word borrowed directly from German, with a slight change of meaning from its original sense of daycare or nursery school.

As you can see, German is quite similar to English. There are, however, differences:
 * German has more letters than and different pronunciations from English.
 * In German the verb is sometimes the last word of a sentence.
 * German has more verb forms than English.
 * German is the only known written language where every noun is capitalized, whether or not it is a proper noun.
 * The word ich (I) is only capitalized if it is the first word of the sentence.
 * German has three different words for you.
 * Adjectives have different endings based on the noun they are modifying in German.
 * German does not have any Present Continuous tense, only Present tense.

However, German is still one of the easiest languages for English speakers to learn. The differences will be tackled over the course of the lessons.

How to Use this Level of the German Textbook
The lessons are meant to be taken in order. You should read and review the German dialogs as often as possible. Many of the dialogs come with audio recordings by native speakers. These recordings are invaluable to learn the German pronunciation. If there is a recording, you can do several kinds of exercises:
 * Read the German dialog and translate it to English with the help of the vocabulary list.
 * Listen to the dialog while you read it and try to understand as much as possible.
 * Listen to the dialog without reading it, pause the playback after each sentence and translate it to English.
 * Listen to the dialog without reading it, pause the playback after each sentence, and write it down in German.
 * Listen to the dialog while reading it, stop after each sentence and repeat the pronunciation.

At the reviews, after every third lesson, go back to look at the previous lessons.

Layout of the Lessons

 * Every lesson has a title at the top.
 * The lesson will introduce several topics, more and more as the lessons progress.
 * Topics are usually introduced by dialogs, which are accompanied by vocabulary lists.
 * Each lesson features several problems and a test at the end. You should write down your answers (either electronically or on paper) before looking at the suggested answers. The act of writing down your answers will help you to learn the spelling.
 * Level I uses a "more than enough" system for the problems. You don't have to do all of the problems if you think you know the material. However, the test may require knowing certain vocabulary, so you need to make sure you know it.

Levels of Completion
On the contents page, you will see filled-in boxes next to each lesson. The number of boxes corresponds to the completeness of the lesson as follows:

 * [[Image:25%.svg]] - The lesson is started, with a lesson overview at least.
 * [[Image:50%.svg]] - At least half of the sections are complete.
 * [[Image:75%.svg]] - Most of the lesson is complete.
 * [[File:100%.svg]] - The entire lesson is complete.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: German/Level I/Introduction


text:
Cookbook talk:Roasted Brined Turkey I

This page uses text adapted from the public domain US Department of Agriculture article FOOD SAFETY OF TURKEY ... from Farm to Table.

title: Cookbook talk:Roasted Brined Turkey I


text:
Trigonometry/For Enthusiasts/Less-Used Trig Identities

Triangle Identities
In addition to the Law of Sines, the Law of Cosines, and the Law of Tangents, there are numerous other identities that apply to the three angles A, B, and C of any triangle (where A+B+C=180° and each of A, B, and C is greater than zero). Some of the most notable ones follow:

 * $$\cos^2(A)+\cos^2(B)+\cos^2(C)+2\cos(A)\cos(B)\cos(C)=1$$

 * $$\sin(A)+\sin(B)+\sin(C)=4\cos\left(\frac{A}{2}\right)\cos\left(\frac{B}{2}\right)\cos\left(\frac{C}{2}\right)$$

 * $$\tan(A)+\tan(B)+\tan(C)=\tan(A)\tan(B)\tan(C)$$

 * $$\tan\left(\frac{A}{2}\right)\tan\left(\frac{B}{2}\right)+\tan\left(\frac{B}{2}\right)\tan\left(\frac{C}{2}\right)+\tan\left(\frac{C}{2}\right)\tan\left(\frac{A}{2}\right)=1$$

 * $$\cot(A)\cot(B)+\cot(B)\cot(C)+\cot(C)\cot(A)=1$$

 * $$\cot\left(\frac{A}{2}\right)\cot\left(\frac{B}{2}\right)\cot\left(\frac{C}{2}\right)=\cot\left(\frac{A}{2}\right)+\cot\left(\frac{B}{2}\right)+\cot\left(\frac{C}{2}\right)$$

 * $$\sin(A)\sin(B)\sin(C)=\frac{1}{\bigl(\cot(A)+\cot(B)\bigr)\bigl(\cot(B)+\cot(C)\bigr)\bigl(\cot(C)+\cot(A)\bigr)}$$

 * $$\frac{\sin(A)+\sin(B)-\sin(C)}{\sin(A)+\sin(B)+\sin(C)}=\tan\left(\frac{A}{2}\right)\tan\left(\frac{B}{2}\right)$$

Pythagoras

 * $$\sin^2(x)+\cos^2(x)=1$$
 * $$1+\tan^2(x)=\sec^2(x)$$
 * $$1+\cot^2(x)=\csc^2(x)$$

These are all direct consequences of Pythagoras's theorem.

Sum/Difference of angles

 * $$\cos(x\pm y)=\cos(x)\cos(y)\mp\sin(x)\sin(y)$$
 * $$\sin(x\pm y)=\sin(x)\cos(y)\pm\sin(y)\cos(x)$$
 * $$\tan(x\pm y)=\frac{\tan(x)\pm\tan(y)}{1\mp\tan(x)\tan(y)}$$

Product to Sum

 * $$2\sin(x)\sin(y)=\cos(x-y)-\cos(x+y)$$
 * $$2\cos(x)\cos(y)=\cos(x-y)+\cos(x+y)$$
 * $$2\sin(x)\cos(y)=\sin(x-y)+\sin(x+y)$$

Sum and difference to product

 * $$A\sin(x)+B\cos(x)=C\sin(x+y)$$, where $$C=\sqrt{A^2+B^2}$$ and $$y=\pm\arctan\bigl(\tfrac{B}{A}\bigr)$$
 * $$\sin(A)\pm\sin(B)=2\sin\left(\frac{A\pm B}{2}\right)\cos\left(\frac{A\mp B}{2}\right)$$
 * $$\cos(A)+\cos(B)=2\cos\sin\left(\frac{A+B}{2}\right)\cos\left(\frac{A-B}{2}\right)$$
 * $$\cos(A)-\cos(B)=-2\sin\left(\frac{A+B}{2}\right)\sin\left(\frac{A-B}{2}\right)$$

Multiple angle

 * $$\cos(2x)=\cos^2(x)-\sin^2(x)=2\cos^2(x)-1=1-2\sin^2(x)$$
 * $$\sin(2x)=2\sin(x)\cos(x)$$
 * $$\tan(2x)=\frac{2\tan(x)}{1-\tan^2(x)}$$
 * $$\cot(2x)=\frac{\cot(x)-\tan(x)}{2}$$
 * $$\csc(2x)=\frac{\cot(x)+\tan(x)}{2}$$
 * $$\cos(3x)=4\cos^3(x)-3\cos(x)$$
 * $$\sin(3x)=-4\sin^3(x)+3\sin(x)$$
 * $$\tan(3x)=\frac{3\tan(x)-\tan^3(x)}{1-3\tan^2(x)}$$
 * $$\cos(4x)=8\cos^4(x)-8\cos^2(x)+1$$
 * $$\sin(4x)=4\sin(x)\cos^3(x)-4\sin^3(x)\cos(x)$$
 * $$\sin^2(4x)=16\Big[\sin^2(x)-5\sin^4(x)+8\sin^6(x)-4\sin^8(x)\Big]$$
 * $$\tan(4x)=\frac{4\tan(x)-4\tan^3(x)}{1-6\tan^2(x)+\tan^4(x)}$$
 * $$\cos(5x)=16\cos^5(x)-20\cos^3(x)+5\cos(x)$$
 * $$\sin(5x)=16\sin^5(x)-20\sin^3(x)+5\sin(x)$$
 * $$\tan(5x)=\frac{5\tan(x)-10\tan^3(x)+\tan^5(x)}{1-10\tan^2(x)+5\tan^4(x)}$$
 * $$\cos(6x)=32\cos^6(x)-48\cos^4(x)+18\cos^2(x)-1$$
 * $$\cos(7x)=64\cos^7(x)-112\cos^5(x)+56\cos^3(x)-7\cos(x)$$
 * $$\sin(7x)=-64\sin^7(x)+112\sin^5(x)-56\sin^3(x)+7\sin(x)$$
 * $$\cos(8x)=128\cos^8(x)-256\cos^6(x)+160\cos^4(x)-32\cos^2(x)+1$$
 * $$\cos(nx)=2\cos(x)\cos\bigl((n-1)x\bigr)-\cos\bigl((n-2)x\bigr)$$
 * $$\sin(nx)=2\cos(x)\sin\bigl((n-1)x\bigr)-\sin\bigl((n-2)x\bigr)$$

These are all direct consequences of the sum/difference formulae

Half angle

 * $$\cos\left(\frac{x}{2}\right)=\pm\sqrt{\frac{1+\cos(x)}{2}}$$
 * $$\sin\left(\frac{x}{2}\right)=\pm\sqrt{\frac{1-\cos(x)}{2}}$$
 * $$\tan\left(\frac{x}{2}\right)=\frac{1-\cos(x)}{\sin(x)}=\frac{\sin(x)}{1+\cos(x)}=\pm\sqrt{\frac{1-\cos(x)}{1+\cos(x)}}$$
 * $$\cos^2\left(\frac{3x}{2}\right)=2\cos^3(x)-\frac{3\cos(x)+1}{2}$$

In cases with $$\pm$$, the sign of the result must be determined from the value of $$\frac{x}{2}$$. These derive from the $$\cos(2x)$$ formulae.

Power Reduction

 * $$\sin^2(x)=\frac{1-\cos(2x)}{2}$$
 * $$\cos^2(x)=\frac{1+\cos(2x)}{2}$$
 * $$\tan^2(x)=\frac{1-\cos(2x)}{1+\cos(2x)}$$

Even/Odd

 * $$\sin(-x)=-\sin(x)$$
 * $$\cos(-x)=\cos(x)$$
 * $$\tan(-x)=-\tan(x)$$
 * $$\csc(-x)=-\csc(x)$$
 * $$\sec(-x)=\sec(x)$$
 * $$\cot(-x)=-\cot(x)$$

Calculus

 * $$\frac{d}{dx}\big[\sin(x)\big]=\cos(x)$$
 * $$\frac{d}{dx}\big[\cos(x)\big]=-\sin(x)$$
 * $$\frac{d}{dx}\big[\tan(x)\big]=\sec^2(x)$$
 * $$\frac{d}{dx}\big[\sec(x)\big]=\sec(x)\tan(x)$$
 * $$\frac{d}{dx}\big[\csc(x)\big]=-\csc(x)\cot(x)$$
 * $$\frac{d}{dx}\big[\cot(x)\big]=-\csc^2(x)$$


text:
Electronics/Batteries

Electrolysis involves an electric field and the motion of electrons through a liquid.

GCSE Science/Electricity

Electrolysis is the decomposition of certain types of substance using electricity. The types of substance that can be split are ionic substances. This just means that they are made of charged ions rather than neutral atoms. {Remember that an ion is just an atom that has either a positive or negative charge}. An example of an ionic substance is common table salt—sodium chloride. The sodium ion has a positive charge, the chlorine ion has a negative charge. It is usually written as Na+Cl-.

Q1) Check in a periodic table, what is the symbol for sodium—Na or Cl?

As you may already know if you've studied the Metals module, a salt is any substance made by combining an acid with an alkali. Acids, alkalis, and therefore all salts are ionic.

Q2) Which of the following substances can be broken up by electricity Sodium chloride, iron sulphate, copper nitrate?

Basic Experimental Setup
Most ionic compounds are not liquid at room temperature. This is a problem because the ions need to be able to move for the electric current to be able to flow. This can be achieved by melting. Look at the electrical setup shown on the right. The electrodes are just two carbon rods connected to a battery. The one connected to the positive electrode is called the anode. The one connected to the negative electrode is called the cathode.

Consider for example the compound lead bromide. This compound is a solid at room temperature but can be molten over a Bunsen flame. So what you would do is put some lead bromide into a beaker. Put the beaker on a tripod over a Bunsen flame. Melt the lead bromide, then put in the electrodes and turn the power supply on at a setting of say 2V. What you would see happening is the anode, is a silvery coating of pure lead forming, and bromine forming at the cathode. The current would continue to flow until all the lead bromide was turned into lead and bromine.

Q3) It takes energy to split up a compound like lead bromide. Where does this energy come from ? Q4) Predict what products you would get at the anode and cathode if copper chloride was the electrolyte.

What happens at the anode
The anode is the positive electrode. It attracts negatively charged ions, because unlike charges attract. The bromine ions move through the melt until they reach the anode. Once they get there, they give up their two extra electrons to become bromine atoms.

Br2- --> Br + 2e-

The electrons flow up the anode to the positive terminal of the battery.

What happens at the cathode
The cathode is the negative electrode. It attracts the positively charged ions. Metal ions are always positive and so the lead ions flow through the melt until they get to the cathode. Once they get there they take two electrons each from the cathode. The electrons flow down the cathode from the negatively terminal of the battery and onto the lead ions.

Pb2+ + 2e- --> Pb

Q5) Solid ionic substances do not conduct electricity and are not split up by it. Why do you think that is?

Quantity calculations (higher tier only)

In the experiment with lead bromide, you saw that lead was deposited at the cathode. If you actually do the experiment you will see that the lead coats the cathode. In this section we will look at how much metal will coat a cathode in a given time.

A scientist performed the following experiment.
 * A copper cathode was carefully cleaned and accurately weighed.
 * It was placed along with an abnode into a solution of copper sulphate.
 * It was connected via a ammeter to a variable power supply.
 * A current was left to run for a given time then the cathode was removed and weighed again.

His results were:

You can see from the results that the total amount of copper deposited depends on both the current and the time it flows. This is because the number of copper atoms that can be made from ions depends on the total amount of charge that flows. The unit of charge is the coulomb.

One coulomb is the amount of charge when one Amp flows for one second (see GCSE Science/Measuring electricity

Q6)Look at the results table above. How much copper is deposited when 1A flows for 3000 seconds?

Q7)How much copper do you predict would be doposited if 1A were to flow for 6000 seconds.

Q8)What about if 2A were to flow for 12000 seconds ?

Electrolysis of Aqueos solutions (Advanced)
Before studying this section check with your teacher to see if you need to.

Earlier on in this module you've learned that ions must be able to move in order for electrolysis to work. If the ions are held rigid {such as in a solid}, they can't move and no electricity will flow. We've looked at how the freeing up of ions can occur by melting the electrolyte. Another way to achieve this is by dissolving th electrolyte in water. The trouble with this method is, there will be mor than one type of ion present.

water partially splits up into ions {this is why it's such a good solvent for ionic compounds}. It splits into hydrogen ions and hydroxide ions.

H2O --> H+ +OH-

So at the cathode there will be two ions present. The Metal ion and the hydrogen ion from the water. Which element is actually produced at the cathode depends on how reactive the metal is. If the metal is very reactive, such as potassium, or sodium, then hydrogen will be produced. If the metal is unreactive such as silver, the metal will be produced.{I hope you learned your displacement reactions in lower school}. To work out which ion wins, the metal or the hydrogen, compare their reactivities in a the reactivity series. The one that is most reactive, will not be produced at the cathode.

A similar situation occurs at the anode. Hydroxide ions {from the water} are usually discharged at the anode ultimately producing oxygen.

OH- --> OH + e-

4OH --> 2H2O + O2.

This is true for most things but if the ions are bromine, chlorine, or fluorine {i.e. a halogen} then the halogen will be produced. {You are unlikely to need to remember this, only understand it}

Q9) Sodium chloride is dissolved in water and subjected to electrolysis. Explain what you see at each of the electrodes.

Answers | <>

A fuel cell is an electrochemical device similar to a battery, but differing from the latter in that it is designed for continuous replenishment of the reactants consumed; i.e. it produces electricity from an external fuel supply as opposed to the limited internal energy storage capacity of a battery.

Typical reactants are hydrogen on the anode side and oxygen on the cathode side. In contrast, conventional batteries consume solid reactants and, once these reactants are depleted, must be discarded, recharged with electricity by running the chemical reaction backwards, or, at least in theory, having their electrodes replaced. Typically in fuel cells, reactants flow in and reaction products flow out, and continuous long-term operation is feasible virtually as long as these flows are maintained.

Fuel cells are also attractive in some applications for their high efficiency and low pollution. Some applications that have been suggested include
 * baseload utility power plants,
 * emergency backup power,
 * off-grid power storage,
 * portable electronics, and
 * electrically-powered vehicles.

Types of fuel cells
There are five generally recognised types of fuel cells, of which two are the main subject of intensive research.

PEM
PEM fuel cells have a disputed acronym, meaning either proton-exchange membrane or polymer-electrolyte membrane, which both are in fact a good description. In this fuel cell, hydrogen is split at the membrane surface in protons, that travel through the membrane, and electrons, that travel through our external electric circuit, and provide our power. The hydrogen ions travel through the water that is entrained in the membrane to the other side, where they are combined with oxygen to form water. Unfortunately, while the splitting of the hydrogen molecule is relatively easy, splitting the stronger oxygen molecule is more difficult, and this causes significant losses that result in a sharp decrease of performance of the fuel cell. The PEM fuel cell is a prime candidate for vehicle and other mobile applications of all sizes down to mobile phones, because of its compactness. However, the water-entraining membrane is crucial to performance: too much water will flood the membrane, too little will dry it; in both cases, power output will drop; water management is a very difficult subject in PEM fuel cells. Furthermore, the platinum catalyst on the membrane is easily poisoned by CO.

PEM systems that use reformed methanol were proposed, as in Daimler Chrysler Necar 5; reforming methanol, i.e. making it react to obtain hydrogen, is however a very complicated process, that requires also purification from the CO the reaction produces. A platinum-ruthenium catalyst is necessary as some CO will unavoidably reach the membrane. The level should not exceed 10 parts per million.

DMFC
A subcategory of PEM is the DMFC, or direct methanol fuel cell; here, the methanol is not reformed, but fed directly to the fuel cell. One does not need complicated reforming, and storage of methanol is much easier than that of hydrogen. However, efficiency is low, due to the high permeation of methanol through the membrane, and the dynamic behaviour is sluggish.

The main manufacturer of PEM is Ballard Power Systems of Vancouver, Canada. Efficiencies of PEM are in the range of 40-50%.

SOFC
Solid oxide fuel cells, or SOFC, are intended mainly for stationary applications (power plants). They work at very high temperatures (some at 1000°C), and their off-gases can be used to fire a secondary gas turbine to improve efficiency. Efficiency could reach as much as 70% in these hybrid systems. This time, it's oxygen being transferred through a solid oxide at high temperature to react with hydrogen on the other side. SOFC have such a high temperature that they can be fed (provided some modifications) with natural gas, that will react to give hydrogen in the fuel cell itself. SOFC are very resistant to poisoning, and can indeed be run on CO, which is a poison for PEM.

Since SOFC are made of ceramic materials, they tend to be brittle; they are therefore unsuited for mobile applications. Furthermore, thermal expansion demands a uniform and slow heating process at startup, that will cause very long startup times: typically, 8 hours are to be expected. Research is going now in the direction of lower-temperature SOFC (600°C), which will enable the use of metallic materials with better mechanical properties and heat conductivity.

MCFC
Molten-carbonate fuel cells (MCFC) are also high-temperature, but in the range of 600°C. Their main problem is corrosion, and the need to operate a high-temperature liquid rather than a solid as in the SOFC.

PAFC
Phosphoric-acid fuel cells (PAFC) are a mature technology that is commercially available. Unfortunately, the phosphoric acid solidifies under 40°C, making startup very difficult. They have been used for stationary applications with an efficiency of about 40%, and many believe they do not offer much potential for further development.

AFC
The alkaline fuel cell (AFC) is the cell that brought the Man to the Moon. Used in Apollo-series missions and on the Space Shuttle, it is a very good fuel cell but for the fact that it is poisoned by CO2. This means that the cell will require pure oxygen, or at least purified air. As this process is relatively expensive, not much development is being done on AFC. NASA has decided they will shift to PEM for the next generation of Space Shuttles.

Science
Fuel cells are electrochemical devices, so they are not constrained by the maximum thermal (Carnot) efficiency as combustion engines are. Consequently, they can have very high efficiencies in converting chemical energy to electrical energy.

In the archetypal example of a hydrogen/oxygen polymer electrolyte membrane (PEM) fuel cell, a proton-conducting polymer membrane separates the anode ("fuel") and cathode sides. Each side has an electrode, typically carbon paper coated with platinum catalyst.

On the anode side, hydrogen diffuses to the anode catalyst where it dissociates into protons and electrons. The protons are conducted through the membrane to the cathode, but the electrons are forced to travel in an external circuit (supplying power) because the membrane is electronically insulating.

On the cathode catalyst, oxygen molecules react with the electrons (which have travelled through the external circuit) and protons to form water.

In this example, the only waste product is water vapor.

Also, there is the possible use of fuel cells at home, to store energy at the cheap off-peak electricity rates and used at peak-use hours. It may even be profitable to sell back some of the energy to the power company, like they do with windmill electric power. Peak power production reaches twice the normal level, which means that the very expensive powerplant capacity is sized for levels used for a short period of time. Also, power plants are most efficient at only one production rate and their efficiency drops off significantly at off-peak rates.

History
The first fuel cell was developed in the 19th century by British scientist Sir William Grove. A sketch was published in 1843. But fuel cells did not see practical application until the 1960s, where they were used in the U.S. space program to supply electricity and drinking water (hydrogen and oxygen being readily available from the spacecraft tanks). Extremely expensive materials were used and the fuel cells required very pure hydrogen and oxygen. Early fuel cells tended to require inconveniently high operating temperatures that were a problem in many applications.

Further technological advances in the 1980s and 1990s, like the use of Nafion as the electrolyte, and reductions in the quantity of expensive platinum catalyst required, have made the prospect of fuel cells in consumer applications such as automobiles more realistic.

The fuel cell industry
Ballard Power Systems is a major manufacturer of fuel cells and leads the world in automotive fuel cell technology. Ford Motor Company and Chrysler are major investors in Ballard. As of 2003, the only major automobile companies pursuing internal development of fuel cells for automotive use are General Motors and Toyota; most others are customers of Ballard.

United Technologies (UTX) is a major manufacturer of large, stationary fuel cells used as co-generation power plants in hospitals and large office buildings. The company has also developed bus fleets that are powered by fuel cells.

Pros and cons of fuel cells in various applications
Their use is controversial in some applications. The hydrogen typically used as a fuel isn't a primary source of energy. It is usually only a source of stored energy that must be manufactured using energy from other sources. Some critics of the current stages of this technology argue that the energy needed to create the fuel in the first place may reduce the ultimate energy efficiency of the system to below that of highly efficient gasoline internal-combustion engines; this is especially true if the hydrogen is generated from electrolysis of water by electricity. On the other hand, hydrogen can be generated from methane (the primary component of natural gas) with approximately 80% efficiency. The methane conversion method releases greenhouse gases, however, and the ideal environmental system would be to use renewable energy sources to generate hydrogen through electrolysis. Other types of fuel cells don't face this problem. For example, biological fuel cells take glucose and methanol from food scraps and convert it into hydrogen and food for the bacteria.

There are practical problems to be overcome as well. Although the use of fuel cells for consumer products is probable in the near future, most current designs won't work if oriented upside down. They currently cannot be scaled to the small size needed by portable devices such as cell phones. Current designs require venting and therefore cannot operate under water. They may not be usable on aircraft because of the risk of fuel leaks through the vents. Technologies for safe refueling of consumer fuel cells are not yet in place.

Among the controversies in the use of hydrogen are: First, the energy used to produce the hydrogen is comparable to the energy in the hydrogen, it is inefficient therefore too expensive. If conventional powerplants were used to produce the hydrogen, at best, there would be no gains in current pollution rates. Second, some have suggested that this is a "stalking horse" to bring back nuclear power, which may be the only commercially viable way to make hydrogen and reduce pollution. Finally, the need to provide the very long, costly and vulnerable thousands of miles of gas lines makes hydrogen too costly without government help.

There are several advantages to hydrogen as well. Clean, renewable energy sources like solar and wind power are non-continuous and unreliable through the course of a day. So power from these sources is not always available at the time it is needed. The electricity produced from solar panels or wind generators could be stored in large battery complexes but this can be expensive and batteries have a limited storage capacity and lifetime. If the electricity is used to produce hydrogen however, the energy can be stored more easily. As a gas hydrogen is not hard to store until it is needed.

Batteries in circuits
Batteries in series can increase or decrease the combined voltage.

Toys use batteries, for example, and it is important to note from the associated drawing(s) which way the batteries are to be inserted into the toy because their voltages can add or subtract as the case may be. To add voltages the + of one battery is connected to the - of the next battery. Some damage may be caused by inserting batteries in the wrong direction.

Batteries in parallel are not usually used; at a given rated voltage each battery is able to provide only a certain maximum current, but to increase the maximum available output current several batteries could be connected in parallel, meaning that all the + terminals are connected together, and so are all of the - terminals.

The life of a battery depends approximately on the value of (current times time), but the chemistry involved can permit a battery that seems to have been finished its lifetime to regain some of its life after some time, after the chemistry was able to do its work.

Many different kinds of batteries exist. They are used for different purposes, using different materials, sizes, rated voltages.

Types of batteries
Reversible, rechargeable, irreversible.

Alkaline = Basic
AA AAA C D 9V All batteries, except the 9V variety, are 1.5V. As alkaline batteries lose their charge, or in Layman's terms "juice", the voltage outputted slowly decreases. This is what causes flashlights to dim and remote controls to lose their effectiveness whilst using the last of the power left in the battery.

Lithium
Lithium batteries are available in rechargeable and "normal" forms. Rechargeable lithium-ion batteries are typically found in small to medium electronics, such as laptops, music players, some cordless mice etc. Lithium batteries have little/no proven research of memory effect. Lithium batteries are also available as single decharge cycle batteries. These batteries are marketed as using lithium to increase life span but offer little/no fiscal advantage over standard alkaline batteries.

Nickel Cadmium (NiCd)
Nickel Cadmium batteries are typically not used in the present but were one of the first easily obtainable cheap rechargeable batteries besides the battery. Nickel Cadmium (AKA NiCd) batteries can typically be found in radio controlled cars, older rechargeable "standard" batteries (AA,AAA, etc.), some wireless mice and many other applications. There is a myth that Nickel-Cadmium batteries have a memory effect, where if they are recharged when still somewhat full, they will lose capacity. laboratory research has proven this false in modern batteries (it does happen, to a small extent in old (pre-1950) sintered-plate NiCds). NiCds do suffer from voltage depression, which is similar to the memory effect, but only occurs when the batteries are overcharged.

Nickel Metal Hydride (NiMH)
NiMH batteries can be looked at as a newer version of NiCd batteries. NiMH batteries are often used in the same applications as NiCd batteries. However, they last longer and don't have voltage depression as severe as NiCd batteries.

Lead Acid
Car and boat batteries are the most common forms of lead acid batteries. In both uses they are typically rated for 12V. They have a high current output and can severely injure a person who was to short the circuit.

Memory effect
The memory effect is a myth that states when the battery is not fully charged before it is recharged, it loses capacity, it "forgets" that it has the capacity. The myth also states that the memory effect can sometimes be reversed by using a conditioner. A battery conditioner almost completely discharges a battery (down to 1 volt in NiCds) and are designed to reverse voltage depression, not memory effect. the memory effect does not exist except in very old (1950 or earlier) sintered plate NiCds. There is no need to use a battery conditioner on any battery to reverse memory effect.

For further reading

 * Electronics/Cells
 * Electronics/Batteries/Care

title: Electronics/Batteries


text: User:Akagu

title: User:Akagu


text:
User talk:68.55.73.12

Hi! Any comments about the LD book? Reply by clicking on "(talk)" and "Post a comment". r3m0t (cont) (talk) 09:27, 3 Apr 2004 (UTC)

title: User talk:68.55.73.12


text:
Cookbook:Marshmallow Rice Squares I

| Dessert

This recipe for quick marshmallow rice squares is super-simple and requires little knowledge of cooking!

Ingredients

 * 1 cup mini marshmallows
 * 1 cup puffed cereal (e.g. Rice Krispies)

Procedure

 * 1) Combine marshmallows and cereal in microwaveable bowl.
 * 2) Microwave for 1–2 minutes, depending on your machine's power.
 * 3) Stir to coat the cereal with marshmallow. Press into a buttered baking pan or dish.
 * 4) Cut it into squares and allow it to cool and set.

title: Cookbook:Marshmallow Rice Squares I


text: Template:Lucid Dreaming/LDAppTOC

title: Template:Lucid Dreaming/LDAppTOC


text:
User talk:212.235.124.23

Um... I see you decided to modify a page of the LD wikibook. PLEASE dont replace it with useless data.

title: User talk:212.235.124.23


text:
Cookbook:Nutrition

Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. Carbohydrates, fats, and proteins are macronutrients, and provide energy. Micronutrients include minerals and vitamins.

Fat
Fats may be classified as saturated or unsaturated depending on their chemical structure. Saturated fats (typically from animal sources) have been a staple in many world cultures for millennia. Unsaturated fats (e.g., vegetable oil) are considered healthier, while trans fats are to be avoided. Saturated and some trans fats are typically solid at room temperature (such as butter or lard), while unsaturated fats are typically liquids (such as olive oil or flaxseed oil). Trans fats are very rare in nature, and have been shown to be highly detrimental to human health, but have properties useful in the food processing industry, such as rancidity resistance.

Protein
An essential part of organisms, proteins are made up of amino acids. Some amino acids can be synthesized by the human body while some must be obtained through food. Proteins are major contributors to cells' functions.

Protein is one of the nutrients that are needed in larger quantities (i.e., macronutrients) along with carbohydrates and fat. Proteins contain 17 kJ/g (4 cal/g) energy.

Sources of protein in the diet include nuts, legumes, grains, eggs, meats and dairy products. There is an ongoing debate about the differences in nutritional quality and adequacy of protein from vegan, vegetarian and animal sources, though many studies and institutions have found that a well-planned vegan or vegetarian diet contains enough high-quality protein to support the protein requirements of both sedentary and active people at all stages of life.

Proteins have a distinct behaviour in cooking compared to fats and carbohydrates. Proteins in general stiffen when heated, for example a egg yolk becomes more solid when heated, because it's rich in protein.

Some proteins are toxic for humans but become edible via cooking, for that reason some legumes must be boiled before they can be eaten.

Carbohydrates
Carbohydrates, also known as carbs, refer to starches (complex carbohydrates) and to sugars (simple carbohydrates). Grain products are rich sources of complex and simple carbohydrates, which make up a large part of foods such as rice, noodles, bread, and other grain-based products.

Strictly speaking, carbohydrates are not necessary for human nutrition because proteins can be converted to glucose, which the body uses for energy. The traditional diet of many peoples consists of nearly no carbohydrates, and these people have been shown to be perfectly healthy. However, carbohydrates require less water to digest than do proteins or fats.

Problems have been cited for the long term effects of a no-carbohydrate diet. These include reduced athletic performance, possible brain damage, and nephrotoxicity. The brain can only utilize carbohydrates for energy, and protein may not supply enough in many cases. The increase in protein means that more ammonia groups need to be removed from the blood.

Fiber
Dietary fiber is a type of carbohydrate that is incompletely absorbed in humans and in some animals. Insoluble dietary fiber consists mainly of cellulose, which is indigestible by humans. Soluble dietary fiber consists of a variety of carbohydrates that dissolve or gelatinize in water. Many of these soluble fibers can be fermented or partially fermented by microbes in the human digestive system. Whole grains, beans and other legumes, fruits (especially plums, prunes, and figs), and vegetables are good sources of dietary fiber.

Vitamins
Vitamins are essential nutrients that must either be ingested or synthesised to maintain health. There are two main varieties: water-soluble and fat-soluble. Because some vitamins are only soluble in fat, a totally fat-free diet can be unhealthy.

 * Vitamin A (also known as retinol) is a fat-soluble vitamin found in dairy products and in liver. Excessive vitamin A can poison you. The body can create vitamin A as needed from beta-carotine, which is water-soluble and not dangerous (large amounts can turn your skin and eyes orange, though). You can get plenty of beta-carotine from carrots, squash, and spinach. Vitamin A deficiency can affect the eyesight, so the popular belief that carrots help you see in the dark is not wholly false.
 * The Vitamin B group of water-soluble vitamins contains a number of separate vitamins. An excess of these vitamins is not harmful.
 * Vitamin B1 (or thiamine) can be found in beef, pork, legumes, yeast, egg yolks, milk, green leafy vegetables, and many grains, nuts, and seeds. Deficiency can cause beriberi.
 * Vitamin B2 (or riboflavin) can be found in beef, dairy products, nuts, and green, leafy vegetables.
 * Vitamnin B3 (or niacin) can be found in fish and poultry meats, liver, nuts, seeds, legumes, and green, leafy vegetables. Deficiency can lead to pellagra.
 * Vitamin C (or ascorbic acid) is a water-soluble vitamin found in citrus fruits and green vegetables. A deficiency can lead to scurvy.
 * Vitamin D (or calciferol) is a fat-soluble vitamin found in oily fish. With sufficient exposure to sunlight, most of the requirement can be met through the synthesis of vitamin D by the skin.
 * Vitamin E (or tocopherol) is a fat-soluble vitamin found in vegetable oils, nuts and green leafy vegetables.

Minerals
Minerals are inorganic chemicals, generally metallic, that are used by the body. Usually the body has a sufficient supply of minerals through eating a variety of foods in the correct amounts. Mineral distribution in the body falls into two categories: bulk minerals, and trace minerals (defined by the USRDA as greater than and less than 200 mg). The minerals required in the largest quantities are generally electrolytes, which include calcium, chloride, magnesium, phosphorus, potassium, and sodium.

Calcium
Calcium is the most abundant mineral in the human body, and is needed to form strong bones and teeth, and is also used for blood, muscle, nervous system transmission, and inter-cellular fluid. Calcium plays a part in the contraction of muscle cells and blood vessels, and the secretion of hormones and enzymes. Some typical sources of calcium include: dairy products (milk, cheese, yogurt), Chinese cabbage, kale, and broccoli.

Sodium
Sodium is found together with chloride as sodium chloride or common salt. In the body, sodium helps to balance the fluids inside the body cells and outside them. A lack of sodium can cause cramps. However too much salt in the body is harmful as it can cause hypertension, a condition that affects the blood system

Magnesium
The fourth most abundant mineral in the body - half of which is found in bones, while the other half is distributed amongst tissues and organs. It is a vital component in muscle and nerve function, immune system function, bone strength, blood sugar and blood pressure, and metabolism and protein synthesis. Most sources of magnesium are green vegetables and whole or unrefined grains and nuts, as magnesium is the central component of chlorophyll molecules, which give the green color of vegetables.

Selenium
A trace mineral that makes antioxidant selenoprotein enzymes, which prevent cellular damage from free radicals, regulate thyroid function, and play a role in the immune system. The amount of selenium in a particular food is related to the amount in the soil of the area the food was produced in. Typically it is found in grains and nuts, but also in the meats of animals that eat grain or plants from selenium-rich soil.

Iron
Iron is needed for the formation of hemoglobin in red blood cells which are responsible for carrying oxygen to all parts of the body. Most sources of iron are animal related (also called heme iron sources) and include beef, turkey, chicken, pork, oysters, crab, and tuna. Other sources, called nonheme iron sources, include beans, tofu, spinach, raisins, molasses, and some cereals and grains.

Zinc
Zinc can be found in almost every cell in the body, and stimulates about 100 different enzyme reactions. It is used by the immune system, for DNA synthesis, for healing wounds, and for normal growth and development during hormonally active periods. Zinc is provided by oysters, beef, pork, chicken, fish, beans, tree nuts, and some dairy products.

Copper
Copper aids in the formation of Red Blood Cells. Copper excess also mimics zinc deficiency and can promote impotence.

title: Cookbook:Nutrition


text:
Indonesian/Lesson 0 Exercise

< Indonesian/Lesson 0

Okay, so now you at least know how to read Indonesian. That's a great start!

Indonesian/Malay has a rhymic quality akin to Italian. And for long, native poets, scribes, and orators have had a penchant of creating sentences that rhyme with each other. Just like in English poetry, the rhyming makes extensive use of the many similar final-sounds of words. To prove my point, let me bring you the Rhyme Game.

Rhyme Game
Objective:
 * 1) To practice your pronunciation of Indonesian through the rhyming pattern in the words
 * 2) To build up your vocabulary, obviously!

Kuku-kukuku kaku (My nails are stiff)
-ku (pronounced -COO) is not very common, but it does contain some important words!

Now that I've established the pattern, can you guess how to pronounce these words?

Cinta itu buta (Love is blind)
Words ending with -ta (-TUH) are often related to love, and to umm... many other things!

(*)the vowel sound in ren- is essentially a schwa, in contrast to gEn- in genta

Can you guess, based on what you've learned?

Tangkap ikan kakap! (Catch the Barramundi fish!)
When you catch and hold onto something, you say -kap (-CUP)! And when you let something be known, you should also say -kap!

Here we go again!

Other Tongue Twisters
If you're feeling especially game after your Indonesian phonetics lesson, have a go at the following tongue twisters:

title: Indonesian/Lesson 0 Exercise


text:
User:Dolohov~enwikibooks

I'm a graduate student in New England in control engineering and computer engineering. I'm hoping to contribute a bit on those subjects, but mostly I plan to contribute to the Cookbook.

title: User:Dolohov~enwikibooks


text:
User talk:Dolohov~enwikibooks

Welcome to Wikibooks. It's always good to have more editors at the Cookbook, so have fun. Just as a reminder, you havn't added and recipes yet, but when you do, please make sure to link to them from the Recipe Index, otherwise, the rest of us won't know they are there.

Oh, and check out Welcome, newcomers for any questions you might have, or ask me on my talk page, or go to the Staff lounge, where someone will answer your question. Gentgeen 03:19, 4 Apr 2004 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Dolohov. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Dolohov~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:10, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 04:54, 19 April 2015 (UTC)

title: User talk:Dolohov~enwikibooks


text:
Latin/Introduction to Nouns (L1)

=Introduction to Nouns=

A noun in Latin is exactly like a noun in English - it is a person, place, thing, or idea. For more information on what a noun is and what words are nouns look at "noun" at Wikipedia. If something is a noun in English, then it is also a noun in Latin.

=Nouns in Latin=

Okay, now that we know that nouns are essentially the same part of speech in both English and Latin, what makes Latin nouns work? Anytime that you see a noun in Latin, you will be able to tell a lot about the noun. For example, if you were to see the noun mensam in a Latin text, you would know a number of things about it immediately. We'll go into how you can tell these things in just a bit, but here's what you can learn from seeing the word. First, the word is almost certainly feminine. Second, it's probably the direct object of a sentence. Third, its singular.

To compare that to English, let's look at the English word "table" (because that's what mensam means!) We can see that it is singular, because the plural is "tables." But what else can we learn about the word? It isn't necessarily a direct object--it could be a subject (The table is large), indirect object (I walked to the table), or direct object (He kicked the table). Also, we don't know its gender because English doesn't use a gender system for nouns. So, why are we able to see these things about Latin words? We know them because Latin nouns "decline" - they change their endings to fit their usage. Mensam and mensa both mean table, but they are used very differently. The difference in the form of a noun gives us information about the word.

When we talk about the form a word in Latin takes, we talk about its "incidents". English nouns typically only have one incident - number (singular vs plural). However, Latin nouns have three:

Gender
All nouns in Latin have gender. This includes not only things which physically have gender (man, woman, boy, girl, mother, husband, etc.) but also inanimate objects like tables. Mensa (table), for example, is feminine just like puella (girl). Sometimes a thing (usually animals or words for people like "student" will have two different nouns, with one masculine and the other feminine. Lupus is a male wolf while lupa is a female wolf.  Discipula is a female student while discipulus is a male student.

What really throws a wrench into this is that Latin does not have two genders. It has three. In addition to masculine and feminine, Latin also has the neuter gender (interestingly enough, this comes from the Latin neuter which means "neither"). Crustulum, a cookie, is a good example of a neuter noun. One might ask, why is a table feminine while a cookie is neuter? The simplest answer is: because that's just the way it is. Sometimes the gender of Latin nouns will make absolutely no sense. At other times, it will. It is best, however, to memorize the gender of each noun you learn.

Case
The next step in analyzing a Latin noun is its case. The case of a noun determines its usage in a sentence. Each noun can be put into any of the cases. If you look above, you can see that you have already seen two different forms of the Latin word for "table". They are in different cases. English for the most part does not use cases, but some pronouns show vestiges of a case system ("who" vs. "whom" vs. "whose" and "they" vs. "them" vs. "their"). We take a fairly intuitive approach to learning those words in English, which is perhaps why so many people have problems with "whom". But in Latin, the case of a noun is extremely important.

The number of cases in Latin is generally considered to be six. This leaves out the locative, which is used very rarely and only for a very limited number of nouns, so we'll leave it out for now as well. We'll start off with the standard six - nominative, accusative, genitive, dative, ablative, and vocative.

Note that all forms in the above chart are singular (we'll talk about number in just a bit). You can see that sometimes a couple different cases will look the same. This happens. It is usually possible to determine the appropriate case from the context of a sentence (for instance, you could say "I walked to the table" but wouldn't say "I walked of the table").

Each noun belongs to a group called a "declension" - all of the nouns in a declension have similar sets of endings. For example, mensa is a first declension noun. All of the other first declension nouns are going to have similar endings. Let's take a look at mensa alongside puella.

We'll explore each of the cases and each of the declensions later.

Number
This should be fairly familiar to everyone (well, except perhaps speakers of Japanese and some other languages, whose nouns do not distinguish between singular and plural). Number refers only to whether a noun is singular (there's only one of it) or plural (there's more than one). Let's take a look at our table again. In English, we can easily see the difference between "table" and "tables" by the ending. Latin is the same. In the accusative case, mensam is singular ("table") while mensas is plural (tables). The ending is determined by the number. However, this can create even more confusion. For example, you can see by the chart above (which shows singular forms) that mensae can be either the genitive singular or dative singular. But guess what? Mensae can also be the nominative or vocative plural!

Obviously, we need a new chart that covers number as well as case.

You can see that mensae appears four times, mensa appears three times, and mensis appears twice. Again, context is necessary in determining which case and number a noun will be in.

Dictionary form of a noun
The dictionary form of a noun includes three things.
 * 1) Nominative singular - This is basically the name of a noun - "nominative" derives from the Latin word nomen which means "name" (nomen, by the way, is in the nominative singular!)
 * 2) Genitive singular - The genitive singular is often the easiest to find the stem of the noun from.  The stem is the base from which endings are added.
 * 3) Gender - Because nouns are always a certain gender, this is something that does not change.  Gender is especially important when adjectives are used (more on adjectives later).  It is usually abbreviated (m/f/n)

So, if we wanted to look up "table" in our handy Latin-to-English dictionary, we would look under:

mensa, mensae, f.

=Summary=

Now you have a working knowledge of what constitutes a Latin noun. You know that each noun belongs to one the five declensions and one of the three genders. You know what the six cases are. You're ready to go onto the next chapter and learn about the first declension and the nominative and accusative cases.

Latin | Lesson 2 - First Declension, Nominative/Accusative Cases

title: Latin/Introduction to Nouns (L1)


text:
Cookbook:Pepper

This article pertains to black, green and white pepper berries (Piper nigrum), also known as peppercorns when dried. Other plants/ingredients commonly known as pepper include:
 * the chili pepper (including the bell pepper), and
 * several Asian spices including 'pink' peppercorns and Szechuan pepper.

The black, white and green peppers are actually the same berries harvested and processed at different stages of ripeness. They are very similar in flavour and texture, with the main difference being the colour. They are commonly used in Western cooking as seasoning.

The pepper berry is one of the most common spices in European cuisine, having been known and prized since antiquity due to its strong flavour. It is said that Alaric the Visigoth demanded from Rome a ransom of gold, silver, and pepper.

Black Pepper
Black pepper is a seasoning produced from the fermented, dried, unripe red berries of the plant Piper nigrum. (The same fruit, when unripe green, can be dried, or preserved in brine or vinegar, to make green peppercorns; or when ripe, dried and dehusked to make white peppercorns.)

Ground black pepper may be found on nearly every dinner table in some parts of the world, accompanied by its constant companion salt.

Cooking with Pepper
Black pepper is generally used when you want it to show up in the dish (especially in a whole or 'cracked' form) and white pepper when you do not want it visible in the finished product.

Pepper added at the beginning of a recipe makes the whole recipe taste peppery. When added at the end of a recipe parts of the recipe taste peppery and other parts don't because the pepper won't be evenly distributed among the food.

Grinding pepper releases flavorful volatile oils that evaporate after time, so the full flavor of pepper is obtained when freshly ground onto food at the end of cooking or after serving.

Kookboek/Peper

title: Cookbook:Pepper


text:
Indonesian/Frontpage

Bahasa Indonesia ~ English

Learning Indonesian for English speakers

Go to contents>>

title: Indonesian/Frontpage


text:
XML - Managing Data Exchange/XHTML

In previous chapters, we have learned how to generate HTML documents from XML documents and XSL stylesheets. In this chapter, we will learn how to convert those HTML documents into valid XHTML. We will discuss why XHTML has evolved as a standard and when it should be used.

The Evolution of XHTML
Originally, Web pages were designed in HTML. Unfortunately most implementations of this markup language allow all sorts of mistakes and bad formatting. Major browsers were designed to be forgiving, and poor code would display with few problems in most cases. This poor code was often not portable between browsers, e.g. a page would render in Netscape but not Internet Explorer or vice versa. The accounting for human error and bad formatting takes an amount of processing power that small handheld devices might not have. Thus when displaying data on handhelds, a tiny mistake can crash the device.

XHTML partially mitigates these problems. The processing burden is reduced by requiring XHTML documents to conform to the much stricter rules defined in XML. Aside from the stricter rules, HTML 4.01 and XHTML 1.0 are functionally equivalent. If a document breaks XML's well-formedness rules, an XHTML-compliant browser must not render the page. If a document is well-formed but invalid, an XHTML-compliant browser may render the page, so a significant number of mistakes still slip through.

In this chapter, we will examine in detail how to create an XHTML document.

The biggest problem with HTML from a design standpoint is that it was never meant to be a graphical design language. The original version of HTML was intended to structure human readable content (e.g. marking a section of text as a paragraph), not to format it (e.g. this paragraph should be displayed in 14pt Arial). HTML has evolved far past its original purpose and is being stretched and manipulated to cover cases that the original HTML designers never imagined.

The recommended solution is to use a separate language to describe the presentation of a group of documents. Cascading Style Sheets (CSS) is a language used for describing presentation. From version 1.1 of XHTML upwards web pages must be formatted using CSS or a language with equivalent capabilites such as XSLT (XSL Transformations). The use of CSS or XSLT is optional in XHTML 1.0 unless the strict variant is used. HTML 4.01 supports CSS but not XSLT.

So What is XHTML?
As you might have guessed, XHTML stands for eXtensible HyperText Markup Language. It is a cross between HTML and XML. It fulfills two major purposes that were ignored by HTML:
 * 1) XHTML is a stricter standard than HTML. XHTML documents must be well-formed just like regular XML. This reduces vagaries and inconsistency between browsers, because browsers do not have to decide how to display a badly-formed page. Malformed XHTML is not allowed. Note 1: Browsers only enforce well-formedness if the MIME type is set to  . If the MIME type is set to , the browser will allow badly-formed documents. There are a large number of 'XHTML' documents on the web that are badly-formed and get away with it because their MIME type is  . Note 2: Browsers are not required to check for validity. See Invalid XHTML below for an example.
 * 2) XHTML allows for modularization (m12n). For different environments different element and attribute subsets can be defined.

The best thing about XHTML is that it is almost the same as HTML! If you know how to write an HTML document, it will be very simple for you to create an XHTML document without too much trouble. The biggest thing that you must keep in mind is that unlike with HTML, where simple errors like missing a closing tag are ignored by the browser, XHTML code must be written according to an exact specification. We will see later that adhering to these strict specifications actually allows XHTML to be more flexible than HTML.

XHTML Document Structure
At a minimum, an XHTML document must contain a DOCTYPE declaration and four elements: html, head, title, and body: The opening  tag of an XHTML document must include a namespace declaration for the XHTML namespace.

The DOCTYPE declaration should appear immediately before the html tag in an XHTML document. It can follow one of three formats.

XHTML 1.0 Strict
The Strict declaration is the least forgiving. This is the preferred DOCTYPE for new documents. Strict documents tend to be streamlined and clean. All formatting will appear in Cascading Style Sheets rather than the document itself. Elements that should be included in the Cascading Style Sheet and not the document itself include, but are not limited to:, nderline , old, talics, and

There are also certain instances where your code needs to be nested within block elements. Incorrect Example:  I hope that you enjoy your stay. Correct Example:  I hope that you enjoy your stay.

XHTML 1.0 Transitional
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> This declaration is intended as a halfway house for migrating legacy HTML documents to XHTML 1.0 Strict. The W3C encourages authors to use the Strict DOCTYPE for new documents. (The XHTML 1.0 Transitional DTD refers readers to the relevant note in the HTML4.01 Transitional DTD.)

This DOCTYPE does not require CSS for formatting; although, it is recommended. It generally tolerates inline elements found where block-level elements are expected.

There are a couple of reasons why you might choose this DOCTYPE for new documents.
 * You require backwards compatibility with browsers that support the formatting elements of XHTML but do not support CSS. This is a very small fraction of general users (less than 1%). Many browsers that don't support CSS don't support HTML 4.0 or XHTML either. However, it may be useful on a corporate intranet that has a larger than normal fraction of very old (pre-2000) browsers.
 * You need to link to frames. Using frames is discouraged as they work badly in many browsers.

XHTML 1.0 Frameset
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd"> If you are creating a page with frames, this declaration is appropriate. However, since frames are generally discouraged when designing Web pages, this declaration should be used rarely.

XML Prolog
Additionally, XHTML authors are encouraged by the W3C to include the following processing instruction as the first line of each document: Although it is recommended by the standard, this processing instruction may cause errors in older Web browsers including Internet Explorer version 6. It is up to the individual author to decide whether to include the prolog.

Language
It is good practice to include the optional  attribute  on the html element to describe the document's primary language. For compatibility with HTML the  attribute should also be specified with the same value. For an English language document use:

The  and   attributes can also be specified on other elements to indicate changes of language within the document, e.g. a French quotation in an English document.

Converting HTML to XHTML
In this section, we will discover how to transform an HTML document into an XHTML document. We will examine each of the following rules:
 * Documents must be well-formed
 * Tags must be properly nested
 * Elements must be closed
 * Tags must be lowercase
 * Attribute names must be lowercase
 * Attribute values must be quoted
 * Attributes cannot be minimized
 * The name attribute is replaced with the id attribute (in XHTML 1.0 both name and id should be used with the same value to maintain backwards-compatibility).
 * Plain ampersands are not allowed
 * Scripts and CSS must be escaped(enclose them within the tags <![CDATA[ and ]]>) or preferably moved into external files.

Documents must be well-formed
Because XHTML conforms to all XML standards, an XHTML document must be well-formed according to the W3C's recommendations for an XML document. Several of the rules here reemphasize this point. We will consider both incorrect and correct examples.

Tags must be properly nested
Browsers widely tolerate badly nested tags in HTML documents. The text above would display as bold and underlined, even though the end tags are not in the proper order. An XHTML page will not display if the tags are improperly nested, because it would not be considered a valid XML document. The problem can be easily fixed.

Elements must be closed
Again, XHTML documents must be considered valid XML documents. For this reason, all tags must be closed. HTML specifications listed some tags as having "optional" end tags, such as the    and    tags. In XHTML, the end tags must be included. What should we do about HTML tags that do not have a closing tag? Some special tags do not require or imply a closing tag. In XHTML, the XML rule of including a closing slash within the tag must be followed. Note that some of today's browsers will incorrectly render a page if the closing slash does not have a space before it (  ). Although it is not part of the official recommendation, you should always include the space ( ) for compatibility purposes.

Here are the common empty tags in HTML:
 * area
 * base
 * basefont
 * br
 * hr
 * img
 * input
 * link
 * meta
 * param

Tags must be lowercase
In HTML, tags could be written in either lowercase or uppercase. In fact, some Web authors preferred to write tags in uppercase to make them easier to read. XHTML requires that all tags be lowercase. This difference is necessary because XML differentiates between cases. XML would read    and   as different tags, causing problems in the above example. The problem can be easily fixed by changing all tags to lowercase.

Attribute names must be lowercase
Following the pattern of writing all tags in lowercase, all attribute names must also be in lowercase. The correct tags are easy to create.

Attribute values must be quoted
Some HTML values do not require quotation marks around them. They are understood by browsers. XHTML requires all attributes to be quoted. Even numeric, percentage, and hexadecimal values must appear in quotations for them to be considered part of a proper XHTML document.

Attributes cannot be minimized
HTML allowed some attributes to be written in shorthand, such as selected or noresize. When using XHTML, attribute minimization is forbidden. Instead, use the syntax  x="x" </tt>, where x is the attribute that was formerly minimized. A complete list of minimized attributes follows:
 * checked
 * compact
 * declare
 * defer
 * disabled
 * ismap
 * nohref
 * noresize
 * noshade
 * nowrap
 * readonly
 * selected
 * multiple

The attribute is replaced with the   attribute
HTML 4.01 standards define a name attribute for the tags <tt> a, applet, frame, iframe, img, </tt> and <tt> map </tt>. XHTML has deprecated the name attribute. Instead, the id attribute is used. However, to ensure backwards compatibility with today's browsers, it is best to use both the name and id attributes. As technology advances, it will eventually be unnecessary to use both attributes and XHTML 1.1 removed name altogether.

Ampersands are not supported
Ampersands are illegal in XHTML. They must instead be replaced with the equivalent character code &amp;.

Image alt attributes are mandatory
Because XHTML is designed to be viewed on different types of devices, some of which are not image-capable, alt attributes must be included for all images. Remember that the img tag must include a closing slash in XHTML!

Scripts and CSS must be escaped
Internal scripts and CSS often include characters like the ampersand and less-than characters. If you are using internal scripts or CSS, enclose them within the tags <tt> <![CDATA[ </tt> and <tt> ]]> </tt>. This will mark them as character data that should not be parsed. If you do not use these tags, characters like & and < will be treated as start-of-character entities (like &nbsp;) and tags (like <b> ) respectively. This will cause your page to behave unpredictably, and it may invalidate your code.

Additionally, the type attribute is mandatory for scripts. The comment tags <tt> </tt> that have traditionally been used to hide JavaScript from noncompliant browsers should not be included. The XML standard states that text enclosed in comment tags may be completely excluded from rendered documents, which would lose all script enclosed in the tags. Also  is not permitted in XHTML documents. You must used node creation methods such as  instead. Confusingly,  will appear to work as expected if the document is incorrectly served with a MIME type of   (the type for HTML documents), instead of   (the type for XHTML documents). If the MIME type is  the document will be parsed as HTML which allows. Parsing the document as HTML defeats the purpose of writing it in XHTML.

Similar changes must be made for internal stylesheets. The type attribute must be included, and the CDATA tags should be used. Because scripts and CSS may complicate an XHTML document, it is strongly recommended that they be placed in external .js and .css files, respectively. They can then be linked to from your XHTML document.

Some elements may not be nested
The W3C recommendations state that certain elements may not be contained within others in an XHTML document, even when no XML rules are violated by the inclusion. Elements affected are listed below.

When to convert
By now, it probably sounds as though converting an HTML document into XHTML is easy, but tedious. When would you want to convert your existing pages into XHTML? Before deciding to change your entire Web site, consider these questions.

 * Do you want your pages to be easily viewed over a nontraditional Internet-capable device, such as a PDA or Web-enabled telephone? Will this be a goal of your site in the future? XHTML is the language of choice for Web-enabled portable devices. Now may be a good time for you to commit to creating an all-XHTML site.
 * Do you plan to work with XML in the future? If so, XHTML may be a logical place to begin. If you head up a team of designers who are accustomed to using HTML, XHTML is a small step away. It may be less intimidating for beginners to learn XHTML than it is to try teaching them all about XML from scratch.
 * Is it important that your site be current with the most recent W3C standards? Staying on top of current standards will make your site more stable and help you stay updated in the future, as you will only have to make small changes to upgrade your site to the newest versions of XHTML as they are approved by the W3C.
 * Will you need to convert your documents to another format? As a valid XML document, XHTML can utilize XSL to be converted into text, plain HTML, another XHTML document, or another XML document. HTML cannot be used for this purpose.

If you answered yes to any of the above questions, then you should probably convert your Web site to XHTML.

MIME Types
XHTML 1.0 documents should be served with a MIME Type of  to Web browsers that can accept this type. XHTML 1.0 may be served with the MIME type  to clients that cannot accept   provided that the XHTML complies with the additional constraints in [Appendix C] of the XHTML 1.0 specification. If you cannot configure your Web server to serve documents as different MIME types, you probably should not convert your Web site to XHTML.

You should check that your XHTML documents are served correctly to browsers that support, e.g. Mozilla Firefox. Use 'Page Info' to verify that the type is correct.

XHTML 1.1 documents are often not backwards compatible with HTML and should not be served with a MIME type of.

Help Converting

 * Strict Alternatives to Deprecated Attributes for Elements in XHTML 1.0 Strict

HTML Tidy
When creating HTML, it's very easy to make a mistake by leaving out an end tag or not properly nesting tags. HTML Tidy is a wonderful application that can be used to correct a number of errors with poorly formed HTML documents and convert it into XHTML. Tidy can also format ugly code to be more readable, including code generated by WYSIWYG editors. HTML Tidy can't generate clean code when it encounters problems it isn't sure of how to fix. In these cases, it will generate an error to let you know where the mistake is located in your document.

A few examples of problems that HTML Tidy can remedy:
 * Missing or mismatched end tags.
 * Improperly nested elements.
 * Mixed up tags.
 * Add a missing "/" to properly close tags.
 * Insert missing tags into lists.
 * Add missing quotes around attribute values.
 * Ability to insert the correct DOCTYPE value based on your code (can also recognize and report proprietary elements).

HTML Tidy can also be customized at runtime using a wide array of command line arguments. It is capable of indenting code to make it more readable as well as replacing FONT, NOBR, and CENTER tags with style tags and rules using CSS. Tidy can also be taught new tags by declaring them in the configuration file.

You can read more about HTML Tidy at the W3C's HTML Tidy site, as well as download the application as a binary or get the source code. There are several sites that offer HTML Tidy as an online service including the W3C and Site Valet.

You can also validate your page using the validator available at http://validator.w3.org/.

When not to convert
You shouldn't convert your Web pages if they will always be served with a MIME type of. Make sure you know how to configure your server or server-side script to perform HTTP content negotiation so that XHTML capable browsers receive XHTML marked as. If you can't set up content negotiation, stick to HTML 4.01. People viewing your Web pages with mainstream browsers will be unable to tell the difference between a valid HTML 4.01 web page and a valid XHTML 1.0 Web page.

Make sure the automated tests you run on your site simulate connections from both XHTML-compatible browsers, e.g. Mozilla Firefox, and non–XHTML-compatiable browsers, e.g. Internet Explorer 6.0. This is particularly important if you use Javascript on your Web site. If maintaining two copies of your test suite is too time consuming, don't convert.

Bear in mind that valid HTML 4.01 Strict documents generally require less effort to convert to XHTML 1.1 than valid XHTML 1.0 Transitional documents. A valid HTML 4.01 Strict document can only contain elements that are valid in XHTML 1.1, although a few attributes may need changing. XHTML 1.0 Transitional documents on the other hand can contain ten element types and more than a dozen attributes that are not valid in XHTML 1.1. The XHTML 1.0 Transitional  element alone has six atrributes that are not supported in XHTML 1.1.

Don't be pressured into using XHTML by people talking vaguely about bad practice. Pin them down to what they mean by bad practice. If they start talking about separation of content and presentation, they have confused the differences between HTML and XHTML with the differences between the Transitional and Strict doctypes. Both XHTML 1.0 Transitional and HTML 4.01 Transitional allow you to mix presentation and content in the same document, i.e. they allow this type of bad practice. Both HTML 4.01 Strict and XHTML 1.0 Strict force you to move the bulk of the presentation (but not all of it) in to CSS or an equivalent language. All four doctypes allow you to use embedded stylesheets, whereas, true separation requires that all CSS and Javascript be moved to external files.

XHTML 1.1
XHTML 1.0 is a suitable markup language for most purposes. It provides the option to separate content and presentation, which fits the needs of most Web authors. XHTML 1.1 enforces the separation of content and presentation. All deprecated elements and attributes have been removed. It also removes two attributes that were retained in XHTML 1.0 purely for backwards-compatibility. The  attribute is replaced by   and   is replaced by. Finally it adds support for ruby text found in East Asian documents.

DOCTYPE
The DOCTYPE for XHTML 1.1 is:

Modularization
The modularization of XHTML, or XHTML m12n, provides suggestions for customizing XHTML, either by integrating subsets of XHTML into other XML applications or extending the XHTML element set. The framework defines two proceses:

 * How to group elements and attributes into "modules"
 * How to combine modules to create new markup languages

The resulting languages, which the W3C calls "XHTML Host Languages", are based on the familiar XHTML structure but specialized for specific purposes. XHTML 1.1 is an example of a host language. It was created by grouping the different elements available to XHTML.

XHTML variations, while possible in theory, have not been widely adopted. There is continuing work being done to develop host languages, but their details are beyond the scope of this discussion.

Invalid XHTML
XHTML-compliant browsers are allowed to render invalid XHTML documents provided that the documents are well-formed. A simple example is given below:

Save the example as  (the .xhtml extension is important) and open the page with Mozilla Firefox. The page will render even though it is invalid.

Answers
Lenguaje XHTML XHTML

title: XML - Managing Data Exchange/XHTML


text:
Latin/First Declension (L2)

=First Declension=

The first declension is a group of Latin nouns with the same endings. It is the most regular of the five declensions, in that the twelve endings (6 cases X 2 numbers) are always exactly the same. All you need to do is find the stem. Most first declension nouns are feminine, though a few notable exceptions are masculine.

Case Endings
We've already seen the first declension in the charts in the introduction to nouns, but let's take a closer look now.

First, the singular:

Now, the plural:

You will have to memorize these endings; you should do this now. Memorize all twelve endings even though this lesson will only use four (nominative singular, nominative plural, accusative singular, accusative plural).

Finding the Stem
How do we determine what the stem (i.e., the part before the ending that remains the same in each case) is and what the ending is? Well, we go back to the dictionary entry that we learn for each word. First, we need to check to see if we have a first declension noun. If the nominative singular ends in -a and the genitive singular ends in -ae, we have a first declension noun.

 * mensa, mensae, f. Table.
 * puella, puellae, f. Girl.

Note how both of those words have the endings that we just said were marks of the first declension nouns. Knowing that -ae is the ending for the genitive singular, all we need to do is delete that ending from the word. So, mensae loses the -ae and becomes mens-. That is what is known as the stem of the word. You can add the necessary ending for whatever case and number is needed to that stem. So, if you want an ablative plural (case ending -is), you would just add that ending to mens- to get mensis.

Dictionary Convention
Often, dictionaries will shorten the entry by just printing the genitive singular ending instead of the entire genitive singular. So, "table" and "girl" will appear as:

 * mensa, -ae, f. Table.
 * puella, -ae, f. Girl.

If you see the -ae notation in an entry, it is clear that the word is a first declension noun.

=Nominative Case=

The nominative, or "name" from the Latin nomen, case is almost always used for the subject of a sentence. For instance, in the sentence "Julia gives" the subject is Julia (what she gives and to whom she's giving it, we don't know). She's the one doing the action. So, if the sentence were in Latin, Julia would have to be in the nominative case. Even in a more complex sentence such as "Julia hesitantly decided that it would be a wonderful idea to destroy the table by repeatedly kicking it", we can still find the subject fairly easily. It's still Julia doing the action.

Now, we're not even going to try translating that second sentence into Latin quite yet. But, we know most of what we need to know to translate the first one. First, we need to know how to say Julia in Latin. Luckily for us, many women's names were treated as first declension nouns in Latin, so:

 * Julia, -ae, f. Julia.

Julia has a stem of Juli- and in the nominative singular (nominative because Julia's the subject, singular because there's only one Julia) the ending is -a. Therefore, we have Julia.

"Julia gives"
We haven't learned any verbs yet and there is a lot to learn about verbs before they can be used well, but for our purpose right now we will just say that dat means "gives". So, if we want to say "Julia gives", the sentence in Latin is:

 * Julia dat.

Your first Latin sentence! Pretty simple, huh? Well, let's add on to it.

=Accusative Case=

The accusative case is often the direct object of a sentence. Take this sentence: "The boy reads a book." We know from our discussion on the nominative case that "the boy" is the subject. "Reads" is our verb, so the boy is reading something. The answer to the question "What is the boy reading?" is the direct object. In this case, the boy is reading a "book". "Book", then, is our direct object and would be in the accusative case in Latin.

"Julia gives a table"
So, going back to our earlier sentence with Julia, let's pick something for Julia to give. Maybe Julia has a lot of tables and wants to get rid of one. We still don't know who is going to get this table, but we can say "Julia gives a table." Recall that table is:

 * mensa, -ae, f. Table.

So, knowing that the stem of the word is mens- and the accusative single ending is -am, the table that Julia gives would be mensam. Because the article "a" from "a table" does not translate into Latin, we know all three of the words we need for our short sentence (dat, Julia, and mensam). But what order do they go in? In all actuality, the words could go in any order and you would be able to translate the sentence, because the case of each of the nouns tells you what its usage is. So, even if we said, "Mensam dat Julia.", you would know that the table cannot be the subject.

In actual Latin, the most common sentence structure is nominative-accusative-verb. Compare this to English subject-verb-object. So, if we use the Latin word order, we get:

 * Julia mensam dat.
 * Julia gives a table.

Note that if we decide Julia has to get rid of more than one table, we could say:

 * Julia mensas dat.
 * Julia gives tables.

The Accusative Case is:
 * Singular Plural

f.-am    -as m.-us   -os n.-um   -a

"The table gives Julia"
If we wanted to turn the tables (excuse the pun) and say that the table gives Julia (completely nonsensical, I know, but grammatically correct), we would have to put "Julia" in the accusative (Juli-am) and "table" in the nominative (mens-a). Then, we would get:

Mensa Juliam dat. The table gives Julia.

=Vocab=

So far we've learned:

 * mensa, -ae, f. table
 * puella, -ae, f. girl
 * Julia, -ae, f. Julia

Let's add a couple more. Make sure you memorize the three above as well as these two following.

 * sapientia, -ae, f. wisdom
 * poeta, -ae, m. poet

Wait a minute! Take a look at "poet" again. See something odd? It's not feminine! Poet is one of the few first declension nouns that are masculine. You don't really need to worry about that too much quite yet, because it does not affect how the noun is used. Later, when we get into adjectives and other things, you will need to know what each noun's gender is. For now, use poeta like you would any of the others and just keep its masculinity in the back of your mind.

=Exercises=

With those vocab words and translating dat as "gives" and amat as "loves", translate the following sentences.

 * 1) Poeta sapientiam dat.
 * 2) Poeta puellas amat.
 * 3) Julia poetas amat.
 * 4) Sapientia mensas dat.
 * 5) Puella Juliam amat.

Answers

=Summary=

Congratulations! You now know four common nouns and one name! You know the case endings for every single first declension word, so that even if you come across one that you've never seen before, you will know what case and number it has. You know how to use the nominative as the subject of a sentence, and how to use the accusative as the direct object.

In other words, you're ready to start learning some verbs. The next chapter, an introduction to verbs, will teach you the basics of Latin verbs.

Lesson 1 - Introduction to Nouns | Latin | Lesson 3 - Introduction to Verbs

L2 Word List

title: Latin/First Declension (L2)


text:
Latin/L2/Answers

First Declension (L2) Answers
These are the answers to the exercises in the "First Declension" chapter.

 * 1) The poet gives wisdom.
 * 2) The poet loves the girls.
 * 3) Julia loves poets.
 * 4) Wisdom gives tables.
 * 5) The girl loves Julia.

Return to First Declension

title: Latin/L2/Answers


text:
XML - Managing Data Exchange/XHTML/Answers

XHTML Chapter => XHTML

XHTML Exercises => Exercises

Answer
1. Change the HTML document below into an XHTML document conforming to the W3C's transitional standard. Validate your page using the validator available at http://validator.w3.org/.

Exercise 1
Below is an example of an invalid HTML document that contains a number of deprecated features. It is also badly structured. The document needs converting to XHTML with the content separated from the presentation.

Exercise 1.a.
a. Change the HTML document into a valid XHTML 1.0 Transitional document. Validate your page using the validator available at http://validator.w3.org/.

The XHTML 1.0 Transitional document:   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  Convert HTML to XHTML XHTML page It is important for your site to be current with the most recent W3C standards. Welcome to my page.

I hope that you enjoy your stay.  XHTML is similar to HTML Validator

Exercise 1.b.
b. Starting with the model answer for question 1.a. identify all deprecated elements and attributes in the document and replace them with CSS in a linked external stylesheet. See HyperText Markup Language/Tag List for details of deprecated elements.

The deprecated features are:
 * the  attribute of the   element;
 * the  element; and
 * the.

A possible stylesheet is:  body { color:blue }

span#welcome { text-decoration:underline /* It is generally a bad idea to underline anything other than hyperlinks. */ }

p.highlight { color:#9900FF; font-size:150%; font-family:Arial,sans-serif /* It is good practice to include one as the CSS generic font families, e.g. sans-serif, as an alternative. */ }

The document with deprecated features removed – note the use of the  and   attributes to provide hooks for the CSS selectors.   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  Convert HTML to XHTML  XHTML page It is important for your site to be current with the most recent W3C standards. Welcome to my page.

I hope that you enjoy your stay. XHTML is similar to HTML Validator

Exercise 1.c.
c. Starting with the model answer for question 1.b. replace all presentational markup with semantic markup and ensure that all inline elements are contained in block-level elements. Change the DOCTYPE to XHTML 1.0 Strict and validate the page with the W3C Markup Validation Service.

The presentational elements are:

The 'paragraph' beginning with a  element is a mixture of inline elements and text and so should be contained in a block-level element such as   (paragraph).

The  (anchor) element is inline and needs enclosing in a block-level element.

 <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">  Convert HTML to XHTML <link rel="stylesheet" type="text/css" href="style.css" /> XHTML page It is important for your site to be current with the most recent W3C standards. Welcome to my page. I hope that you enjoy your stay. XHTML is similar to HTML Validator

XHTML Chapter => XHTML

XHTML Exercises => Exercises


text:
User:Paul~enwikibooks

I'm a PhD mathematician with some teacher training under my belt, and I'm very frustrated with the Maths textbook area on this site - there appears to be no focus for contributions.

Answer this: Are we trying to create a seminal work on mathematics that has usefuls tidbits of the basis on arithmetics that university professors would find insightful, or are we instead trying to teach basic arithmetic to an 11 year old?

It seems that the current pages are achieving neither.

title: User:Paul~enwikibooks