text:
Talk:Group action

Utterly unhelpful introductory sentence
"In mathematics, an action of a group is a way of interpreting the elements of the group as "acting" on some space in a way that preserves the structure of that space."

Unfortunately, introducing a concept (group action) by using one of the words in the concept (action) — in quotes, yet ("acting") — is worse than unhelpful. It is totally exasperating to anyone trying to understand the concept. It is the last thing we need in Wikipedia.2602:306:CF5D:1270:4023:7D48:4830:C217 (talk) 20:11, 27 August 2017 (UTC)

 * I reworded the first sentence in the lead. I think this is more clear.  In a mathematics article, describing a concept in simply understood terms, before the technical definition is made, is often difficult.—Anita5192 (talk) 21:54, 27 August 2017 (UTC)

Baseline dot notation
An editor recently changed all the center dot notations to baseline dots for the sake of uniformity in the article. I reverted, claiming that this was the wrong choice, with the intention of switching all the baseline dots to centered dots. Looking at the page I realized that this would be a mammoth job and the thought occurred to me that this might just be an English variant issue, and I should revert myself. All the references that I have checked either use a center dot or simple juxtaposition for the group action. I am not claiming any type of expertise here and am seriously asking where the baseline dot notation may be common? --Bill Cherowitzo (talk) 16:39, 18 September 2017 (UTC)
 * Apparently the baseline dot notation was introduced in 2012, see . I have never seen this notation outside of this article, but that doesn't mean much. Tea2min (talk) 09:36, 19 September 2017 (UTC)

 * I've seen it used (and used it myself a long time ago) but I've always assumed that it was only out of laziness or not knowing the use of \cdot in latex. So it would not be out of place for this article to do so :) jraimbau (talk) 14:50, 19 September 2017 (UTC)

I am thinking that I have seen this notation before and the mental image I have is of some older typewritten monographs (pre-TeX, when you used to have to hand off your manuscript to a secretary to type). My feeling is that if there is some segment of the population that regularly uses this notation, we should keep it (and the 2012 introduction into this article makes me think that this might be the case), but if it is only of nostalgic value then by the "principle of common usage" (don't go looking for a policy by that name, its my own terminology) we should change this to centered dot notation.--Bill Cherowitzo (talk) 17:15, 19 September 2017 (UTC)

I think the period is only used in older texts, so we should probably go with centered dots or juxtaposition. I lean towards the former, because using juxtaposition for both the group operation and the action might confuse newcomers. I have no strong opinions on the matter though; I would only argue that we should be consistent throughout the article. AxelBoldt (talk) 17:04, 21 September 2017 (UTC)

 * I've converted to the center dots. I hope I've gotten them all. --Bill Cherowitzo (talk) 04:56, 23 September 2017 (UTC)

 * Thank you! 67.198.37.16 (talk) 07:01, 5 December 2023 (UTC)

Move discussion in progress
There is a move discussion in progress on Talk:Permutation representation (disambiguation) which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 20:31, 15 November 2017 (UTC)

Transitivity of Special Linear Group
The transitivity line of the section on types of group actions claims that the special linear group is transitive over a vector space. Surely this need not be true if the vector space has dimension 1 and the field is non-trivial. The special linear group of the real line is just multiplication by 1, which is not a transitive action on the reals. — Preceding unsigned comment added by 140.194.194.252 (talk) 14:25, 22 June 2018 (UTC)

Orbit-stabilizer theorem
I replaced the article's statement of the orbit-stabilizer theorem by a more straightforward statement, and was reverted by with the edit summary "though the current version is a bit too abstract this one is not clearer". I disagree. I understood the statement which I added at first reading. The current statement requires the reader to look up "image" and coimage; and I have still not understood it after at least six readings. The current version is also followed by mention of "G-sets", while providing no clue about what a G-set is. I accept that the current version may be preferred by readers who already know and understand the orbit-stabilizer theorem, but it is little use to readers who have come to the article hoping to find out. Maproom (talk) 13:47, 25 November 2018 (UTC)

 * I agreed that the version before yours was too abstract, and just changed it (with a precise reference to a standard text in algebra).
 * Your version was in my opinion worse : the citation comes from some notes on a specific problem and the statement that you reproduced is specific to the situation there, and concerns the induced action of the group on the set of subsets of X, not the action on the set X itself. In my opinion this elads to it being easily misinterpreted as that fact was not made clear. jraimbau (talk) 13:54, 25 November 2018 (UTC)

Covering Space Action
I was wondering, if we can add the following definition to the second list in the Types of actions section:

 * Covering space action if every point $$ x \in X $$ has a neighbourhood $$ U $$ such that $$\{g \in G : g \cdot U \cap U \neq \emptyset\} = e $$.

Since in the book Algebraic topology Allen Hatcher writes

"This is not standard terminology, but there does not seem to be a universally accepted name for [it]."

I assume this might be a matter of debate whether to list this as a standard definition. But since this book was (and still is) quite influential in the field of algebraic topology I'm asking if it justifies to just do it. K!r!93 (talk) 20:54, 22 April 2019 (UTC)

Section on orbit-stabilizer theorem needs expanding
I've read the paragraph about the orbit-stabiliser theorem many times now and I just can't understand it. The text is too condensed - it seems to try to introduce the theorem and prove it in a single sentence, and it does so in a way that doesn't build on what comes before it in the article. (This same sentence introduces the notion of coset for the first time, and also uses the word "translate" in a sense that's not familiar to me.)

It seems like this is a pretty important theorem, and the article would greatly benefit from spending a bit more time introducing the concepts behind the theorem and explaining what it shows. Nathaniel Virgo (talk) 19:32, 12 June 2019 (UTC)

 * I added some explanation and a very simplistic example. If you are fine with it now, you can remove the tag.(I am not going to explain coset, there is a link to the corresponding page.)ChristianTS (talk) 15:52, 1 October 2019 (UTC)

Still utterly unhelpful intro sentence
"In mathematics, a group action is a formal way of interpreting the manner in which the elements of a group correspond to transformations of some space in a way that preserves the structure of that space."

From this we might conclude:

1. There is some space. 2. It has a structure (whatever that means). 3. There can be transformations of that space. 4. ... which might or might not preserve that structure. 5. There is a group. 6. An element of that group corresponds to (one or some of?) the transformations mentioned in (3, but only if preserving structure (4). 7. There is a manner of 6. 8. There are interpretations of the manner in 7 9. Among the interpretations of 8, some are formal. 10. A group action is one of the formal interpretations of (9).

In short, this is a word salad with so many indirections and hedges that it is either incomprehensible or incorrect. For starters, I am pretty sure that a "group action" is not a "way of interpreting". There may be a "way of interpreting" that allows us to perceive "group action" as a such-and-such, but the group action is not the way-of-interpreting per se.

Perhaps this was the intended meaning: "In mathematics, a group action is a transformation of a space to a new space that has particular structural properties in common with the first space." Gwideman (talk) 23:57, 25 November 2019 (UTC)

 * While I agree that the introduction of this article is not easy to understand, I would object to your proposed formulation, "In mathematics, a group action is a transformation of a space to a new space that has particular structural properties in common with the first space." Two points:
 * Every group element gives a transformation of the base space to itself, so both spaces you wrote about are the same.
 * A group action is not a single transformation but a family of transformations, parameterized by elements of some group, with the parameterization subject to the identity and the composability requirements.
 * (That being said, I am unhappy with the phrasing in the article, "in a way that preserves the structure of that space". To me this seems to imply that group action needs to be faithful, but here I'm probably reading to much into that sentence.)
 * Anyway, it obviously is quite hard to capture the idea of a group action in prose. – Tea2min (talk) 09:56, 26 November 2019 (UTC)

 * I agree that the first sentence must be changed and that Gwideman's suggestion is not better. However, the whole lead is too long and confusing. So, fixing the first sentence needs to completely rewrite the whole lead (and probably the whole article). Nevertheless, I suggest the following for the first paragraph: D.Lazard (talk) 10:54, 26 November 2019 (UTC)

 * I reworded the first sentence on 14:52, August 27, 2017 with this edit in an attempt to improve it after another editor complained about the previous wording (see Utterly unhelpful introductory sentence, above). I agree that a definition of a group action is difficult to capture in one sentence in such a way that is accurate, complete, and easy for a layman to understand. I like the introduction proposed by D.Lazard above.—Anita5192 (talk) 18:27, 26 November 2019 (UTC)

 * I have been bold and implemented my proposed introduction, before remarking 's edit. I Have also rewritten the paragraph on permutations. I'll continue by removing non-encyclopedic content that has no real content, or does not belongs to this lead. D.Lazard (talk) 18:48, 26 November 2019 (UTC)

 * First, thanks for paying some attention to this. The new formulation of the intro paragraph now suffers from having two only-partially-parallel ideas muddled into the lead sentence, after which it's difficult to tell which of these ideas subsequent sentences and clauses refer back to.

 * In the following, I have pulled apart these two separate lines of discussion into simpler sentences in an effort to reveal what refers back to what. I noted some ambiguities in [brackets].

 * 1. In mathematics, a group action can act on either a space or a mathematical structure.
 * 2. A group action on a space is a group homomorphism of the group into transformations of the space. [What does "of the group" refer back to here?]
 * 3. A group action on a mathematical structure is a group homomorphism of the group into automorphisms of the structure. In this case the group action also acts on everything that is built with that structure. [Again, what does "of the group" refer back to?]
 * 4. For example the group of Euclidean isometries acts on Euclidean space and also on the figures drawn in it. In particular, it acts on the set of all triangles. [So this is an example of group action on a space, right?]
 * 5. Similarly, the group of symmetries of a polyhedron acts on the vertices, the edges, and the faces of the polyhedron. [Again an example of group action on a space, right?]
 * 6. [So no example of group action on a mathematical structure?]
 * Gwideman (talk) 01:38, 29 November 2019 (UTC)
 * I'll take a shot.
 * A group action of a group on a set is a collection of transformations from the set to itself, such that the collection of transformations under function composition is compatible with, or commutes with multiplication in the group. Similarly, a group action on a mathematical structure is a group homomorphism of the group into the automorphism group of the structure.
 * There. Perhaps that is less garbled? 67.198.37.16 (talk) 07:57, 5 December 2023 (UTC)
 * The new version of the first sentence is slightly better than the preceding one, but it remains overly technical for this place in the article, since the meaning of the definition can only be understood by people knowing already the subject. Instead, the lead must begin with an explanation of the need of the concept. Something like
 * I do not imagine a better way for fixing the issues raised by the opening post of this thread. Nevertheless, my prose may certainly be improved. D.Lazard (talk) 17:43, 5 December 2023 (UTC)
 * The part in green sounds entirely fine to me. It's late at night, and all of my brain cells have curled up under the covers and are waiting to go to sleep. So please do copy that in. My only suggesting is that the More precisely ... bit start a new paragraph, so that it's not a big blob of text. I like More precisely ... rather than More technically... since the goal is increased precision, rather than increased complexity. I'll check back later to see if something more eloquent pops into my mind. 67.198.37.16 (talk) 05:10, 6 December 2023 (UTC)
 * To also address the comment immediately below, I'm thinking that perhaps a section of 2 or 3 or 4 very basic informal examples be provided, before the definition. Oddly, the intuitvely simplest example I can think of is mathematically complicated, but it works: the rotation group on 3D objects. The canonical imagine flipping a cell phone over, and then turning it to the right; just don't say "non-commutative" and we'll be OK. This can be done with all-words, no formulas. Then perhaps rotations in a plane, because some relatively simple formulas can be given for that, and finally, the simplest/hardest to explain, the permutation group on three objects. Its quite abstract, can lead to confusion, but also allows some notational gymnastics, right before kicking into the formal definition. I'm unlikely to write any of this, unless bitten by some wild hare. 67.198.37.16 (talk) 05:27, 6 December 2023 (UTC)
 * To also address the comment immediately below, I'm thinking that perhaps a section of 2 or 3 or 4 very basic informal examples be provided, before the definition. Oddly, the intuitvely simplest example I can think of is mathematically complicated, but it works: the rotation group on 3D objects. The canonical imagine flipping a cell phone over, and then turning it to the right; just don't say "non-commutative" and we'll be OK. This can be done with all-words, no formulas. Then perhaps rotations in a plane, because some relatively simple formulas can be given for that, and finally, the simplest/hardest to explain, the permutation group on three objects. Its quite abstract, can lead to confusion, but also allows some notational gymnastics, right before kicking into the formal definition. I'm unlikely to write any of this, unless bitten by some wild hare. 67.198.37.16 (talk) 05:27, 6 December 2023 (UTC)

I have implemented my above suggestion, and cleaned accordingly the remainder of the lead. So, this section can be closed, and, if there is some problems with this new version, this must be discussed in a new section. Similarly the discussion on the remainder of the article must also occur in new sections. In this long section, there are some posts of this sort. I leave to their authors to repost them in a specific section. D.Lazard (talk) 20:47, 11 December 2023 (UTC)

Requested move 22 March 2020

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: page moved. wbm1058 (talk) 17:29, 29 March 2020 (UTC)

– per WP:PRIMARYTOPIC. For example, Group action (sociology) only has 7 incoming links (once dabs, see alsos, and links from nav boxes are excluded) (a couple of these links are questionable, one of which is now at AfD). In contrast, Group action (mathematics) has over 400 (472 total, although this might include some dabs and see alsos...I'm not going to count individually). A comparison of |Group_action_(sociology) page views favors this as well. –Deacon Vorbis (carbon • videos) 13:13, 22 March 2020 (UTC)
 * Group action (mathematics) → Group action
 * Group action → (deleted to make way for page move)

 * Support per nom. The math article is clearly the primary topic in a WP:TWODABS situation. Just point to the sociology article in a hatnote. Station1 (talk) 20:56, 22 March 2020 (UTC)

 * Support: clear WP:PRIMARYTOPIC for the mathematics usage. — MarkH21talk 11:07, 27 March 2020 (UTC)

 * Support: per nom. Clearly a primary topic and a hatnote will suffice to redirect readers.--Bill Cherowitzo (talk) 19:09, 28 March 2020 (UTC)
 * Comment. You do not actually want to create a page titled (deleted to make way for page move); that is an invalid page title. What is/should actually be proposed here is to move Group action → Group action (disambiguation). If then, you want to delete Group action (disambiguation), then fine. This avoids having page histories of two different topics sitting on the same title. – wbm1058 (talk) 17:09, 29 March 2020 (UTC)

 * The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

This article is not clear, it has very obscure notation, please use clearer notation.
Is this change correct? From this text:
 *  Left group action
 * If $G$ is a group with identity element $e$, and $X$ is a set, then a (left) group action $α$ of $G$ on $X$ is a function
 * $$\alpha\colon G \times X \to X,$$
 * that satisfies the following two axioms:
 * that satisfies the following two axioms:
 * that satisfies the following two axioms:

 * Identity:
 * $$\alpha(e,x)=x$$
 * Compatibility:
 * $$\alpha\left(g,\alpha\left(h,x\right)\right)=\alpha\left(gh,x\right)$$
 * }
 * (with $α(g, x)$ often shortened to $gx$ or $g ⋅ x$ when the action being considered is clear from context):
 * (with $g ⋅ x$ often shortened to $g^{−1}$ or $Sym(X)$ when the action being considered is clear from context):
 * (with $α(g, x)$ often shortened to $gx$ or $g ⋅ x$ when the action being considered is clear from context):

 * Identity:
 * $$e\cdot x = x$$
 * Compatibility:
 * $$g\cdot(h\cdot x) = (gh) \cdot x$$
 * }
 * for all $g$ and $h$ in $G$ and all $x$ in $X$.
 * The group $G$ is said to act on $X$ (from the left). A set $X$ together with an action of $G$ is called a (left) $G$-set.
 * From these two axioms, it follows that for any fixed $g$ in $G$, the function from $X$ to itself which maps $x$ to $g ⋅ x$ is a bijection, with inverse bijection the corresponding map for $g^{−1}$. Therefore, one may equivalently define a group action of $G$ on $X$ as a group homomorphism from $G$ into the symmetric group $Sym(X)$ of all bijections from $X$ to itself.>
 * The group $G$ is said to act on $e$ (from the left). A set $X$ together with an action of $α$ is called a (left) $G$-set.
 * From these two axioms, it follows that for any fixed $X$ in $g$, the function from $h$ to itself which maps $G$ to $g ⋅ x$ is a bijection, with inverse bijection the corresponding map for $α(g, x)$. Therefore, one may equivalently define a group action of $x$ on $X$ as a group homomorphism from $G$ into the symmetric group $g ⋅ x$ of all bijections from $X$ to itself.>
 * From these two axioms, it follows that for any fixed $X$ in $G$, the function from $G$ to itself which maps $g$ to $gx$ is a bijection, with inverse bijection the corresponding map for ᙭᙭᙭. Therefore, one may equivalently define a group action of $G$ on $X$ as a group homomorphism from $x$ into the symmetric group ᙭᙭᙭ of all bijections from $G$ to itself.>
 * From these two axioms, it follows that for any fixed $X$ in $G$, the function from $X$ to itself which maps ⇭⇭⇭ to ᙭᙭᙭ is a bijection, with inverse bijection the corresponding map for ᙭᙭᙭. Therefore, one may equivalently define a group action of ⇭⇭⇭ on ⇭⇭⇭ as a group homomorphism from ⇭⇭⇭ into the symmetric group ᙭᙭᙭ of all bijections from ⇭⇭⇭ to itself.>

to

 *  Left group action
 * If ⇭⇭⇭ is a group $$\langle X,\cdot,e,{}^{-1}\rangle$$ with identity element ⇭⇭⇭, and ⇭⇭⇭ is a set, then a (left) group action ⇭⇭⇭ of ⇭⇭⇭ on ⇭⇭⇭ is a function
 * $$\alpha\colon G \times X \to X,$$
 * that satisfies the following two axioms:
 * that satisfies the following two axioms:
 * that satisfies the following two axioms:

 * Identity:
 * $$\alpha(e,x)=x$$
 * Compatibility:
 * $$\alpha\left(g,\alpha\left(h,x\right)\right)=\alpha\left(g\circ h,x\right)$$
 * }
 * (with ᙭᙭᙭ often shortened to ᙭᙭᙭ or ᙭᙭᙭ when the action being considered is clear from context):
 * (with ᙭᙭᙭ often shortened to ᙭᙭᙭ or ᙭᙭᙭ when the action being considered is clear from context):
 * (with ᙭᙭᙭ often shortened to ᙭᙭᙭ or ᙭᙭᙭ when the action being considered is clear from context):

— Preceding unsigned comment added by 2806:106e:b:c6e9:174:9fc8:e165:a58f (talk) 08:03, 27 December 2021 (UTC)
 * Identity:
 * $$e\cdot x = x$$
 * Compatibility:
 * $$g\cdot(h\cdot x) = (g\circ h) \cdot x$$
 * }
 * for all ⇭⇭⇭ and ⇭⇭⇭ in ⇭⇭⇭ and all ⇭⇭⇭ in ⇭⇭⇭.
 * The group ⇭⇭⇭ is said to act on ⇭⇭⇭ (from the left). A set ⇭⇭⇭ together with an action of ⇭⇭⇭ is called a (left) ⇭⇭⇭-set.
 * From these two axioms, it follows that for any fixed ⇭⇭⇭ in ⇭⇭⇭, the function from ⇭⇭⇭ to itself which maps ⇭⇭⇭ to ᙭᙭᙭ is a bijection, with inverse bijection the corresponding map for ᙭᙭᙭. Therefore, one may equivalently define a group action of ⇭⇭⇭ on ⇭⇭⇭ as a group homomorphism from ⇭⇭⇭ into the symmetric group ᙭᙭᙭ of all bijections from ⇭⇭⇭ to itself.
 * The group ⇭⇭⇭ is said to act on ⇭⇭⇭ (from the left). A set ⇭⇭⇭ together with an action of ⇭⇭⇭ is called a (left) ⇭⇭⇭-set.
 * From these two axioms, it follows that for any fixed ⇭⇭⇭ in ⇭⇭⇭, the function from ⇭⇭⇭ to itself which maps ⇭⇭⇭ to ᙭᙭᙭ is a bijection, with inverse bijection the corresponding map for ᙭᙭᙭. Therefore, one may equivalently define a group action of ⇭⇭⇭ on ⇭⇭⇭ as a group homomorphism from ⇭⇭⇭ into the symmetric group ᙭᙭᙭ of all bijections from ⇭⇭⇭ to itself.
 * From these two axioms, it follows that for any fixed ⇭⇭⇭ in ⇭⇭⇭, the function from ⇭⇭⇭ to itself which maps ⇭⇭⇭ to ᙭᙭᙭ is a bijection, with inverse bijection the corresponding map for ᙭᙭᙭. Therefore, one may equivalently define a group action of ⇭⇭⇭ on ⇭⇭⇭ as a group homomorphism from ⇭⇭⇭ into the symmetric group ᙭᙭᙭ of all bijections from ⇭⇭⇭ to itself.

The notation in this article is obscure
I thought that rewriting it with a clearer notation I could understand it, but I failed. Here some questions:

What does it mean to multiply a group, which is a structure, by a set?

Said in other way: What is an action?

Is the "⋅" in ᙭᙭᙭ the group operation, or what is it?

Please rewrite it in a more readable way.

I tried but I'm not mathematician.

— Preceding unsigned comment added by 2806:106e:b:c6e9:174:9fc8:e165:a58f (talk) 08:03, 27 December 2021 (UTC)

 * For a group G operating on a space X, the dot is commonly used to denote both the binary operation of the group,
 * ⋅ : G × G → G,
 * and also the action of elements of the group G on elements of the space X,
 * ⋅ : G × X → X,
 * and the context makes clear which is meant. What's more, both the group operation and the group action are commonly written just using juxtaposition, without any symbol to denote the given operation. I see why this can be confusing on a first reading. The notation is however common (and perfectly standard). (Think matrixes operating on vectors.)
 * — Tea2min (talk) 06:35, 28 December 2021 (UTC)
 * I changed the article to say this, which is perhaps more clear?
 * ''It can be notationally convenient to curry the action $$\alpha$$, so that, instead, one has a collection of transformations $$\alpha_g:X\to X$$, with one transformation $$\alpha_g$$ for each group element $$g\in G$$. The identity and compatibility relations then read
 * $$\alpha_e(x) = x$$
 * ''and
 * $$\alpha_g(\alpha_h(x)) = (\alpha_g \circ \alpha_h)(x) = \alpha_{gh}(x)$$
 * ''with $$\circ$$ being function composition. The second axiom then states that the function composition is compatible with the group multiplication; they form a commutative diagram. This axiom can be shortened even further, and written as $$\alpha_g \circ \alpha_h = \alpha_{gh}$$
 * ''With the above understanding, it is very common to avoid writing $$\alpha$$ entirely, and to replace it with either a dot, or with nothing at all. Thus, ᙭᙭᙭ can be shortened to ᙭᙭᙭ or ᙭᙭᙭, especially when the action is clear from context. The axioms are then
 * $$e\cdot x = x$$
 * $$g\cdot(h\cdot x) = (gh) \cdot x$$
 * Perhaps this removes the confusion of what this supposed to be all about? 67.198.37.16 (talk) 08:36, 5 December 2023 (UTC)

title: Talk:Group action


text:
Gzip

gzip is a file format and a software application used for file compression and decompression. The program was created by Jean-loup Gailly and Mark Adler as a free software replacement for the compress program used in early Unix systems, and intended for use by GNU (from where the "g" of gzip is derived). Version 0.1 was first publicly released on 31 October 1992, and version 1.0 followed in February 1993.

The decompression of the gzip format can be implemented as a streaming algorithm, an important feature for Web protocols, data interchange and ETL (in standard pipes) applications.

File format
gzip is based on the DEFLATE algorithm, which is a combination of LZ77 and Huffman coding. DEFLATE was intended as a replacement for LZW and other patent-encumbered data compression algorithms which, at the time, limited the usability of the compress utility and other popular archivers.

"gzip" is often also used to refer to the gzip file format, which is:
 * a 10-byte header, containing a magic number, the compression method ( for DEFLATE), 1-byte of header flags, a 4-byte timestamp, compression flags and the operating system ID.
 * optional extra headers as allowed by the header flags, including the original filename, a comment field, an "extra" field, and the lower half of a CRC-32 checksum for the header section.
 * a body, containing a DEFLATE-compressed payload
 * an 8-byte trailer, containing a CRC-32 checksum and the length of the original uncompressed data, modulo 232.

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gzip is not to be confused with the ZIP archive format, which also uses DEFLATE. The ZIP format can hold collections of files without an external archiver, but is less compact than compressed tarballs holding the same data, because it compresses files individually and cannot take advantage of redundancy between files (solid compression). The gzip file format is also not to be confused with the that of the compress utility, based on LZW, with extension .Z; however, the gunzip utility is able to decompress .Z files.

Implementations
Various implementations of the program have been written. The most commonly known is the GNU Project's implementation using Lempel-Ziv coding (LZ77). OpenBSD's version of gzip is actually the compress program, to which support for the gzip format was added in OpenBSD 3.4. The 'g' in this specific version stands for gratis. FreeBSD, DragonFly BSD and NetBSD use a BSD-licensed implementation instead of the GNU version; it is actually a command-line interface for zlib intended to be compatible with the GNU implementations' options. These implementations originally come from NetBSD, and support decompression of bzip2 and the Unix pack format.

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Damage recovery
Data in blocks prior to the first damaged part of the archive is usually fully readable. Data from blocks not demolished by damage that are located afterward may be recoverable through difficult workarounds.

Derivatives and other uses
The tar utility included in most Linux distributions can extract .tar.gz files by passing the z option, e.g., tar -zxf file.tar.gz, where  instructs decompression,   means extraction, and   specifies the name of the compressed archive file to extract from. Optionally,  (verbose) lists files as they are being extracted.

zlib is an abstraction of the DEFLATE algorithm in library form which includes support both for the gzip file format and a lightweight data stream format in its API. The zlib stream format, DEFLATE, and the gzip file format were standardized respectively as RFC 1950, RFC 1951, and RFC 1952.

The gzip format is used in HTTP compression, a technique used to speed up the sending of HTML and other content on the World Wide Web. It is one of the three standard formats for HTTP compression as specified in RFC 2616. This RFC also specifies a zlib format (called "DEFLATE"), which is equal to the gzip format except that gzip adds eleven bytes of overhead in the form of headers and trailers. Still, the gzip format is sometimes recommended over zlib because Internet Explorer does not implement the standard correctly and cannot handle the zlib format as specified in RFC 1950.

zlib DEFLATE is used internally by the Portable Network Graphics (PNG) format.

Since the late 1990s, bzip2, a file compression utility based on a block-sorting algorithm, has gained some popularity as a gzip replacement. It produces considerably smaller files (especially for source code and other structured text), but at the cost of memory and processing time (up to a factor of 4).

AdvanceCOMP, Zopfli, libdeflate and 7-Zip can produce gzip-compatible files, using an internal DEFLATE implementation with better compression ratios than gzip itself—at the cost of more processor time compared to the reference implementation.

Research published in 2023 showed that simple lossless compression techniques such as gzip could be combined with a k-nearest-neighbor classifier to create an attractive alternative to deep neural networks for text classification in natural language processing. This approach has been shown to equal and in some cases outperform conventional approaches such as BERT due to low resource requirements, e.g. no requirement for GPU hardware.

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

title: Gzip


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General anaesthetic

General anaesthetics (or anesthetics) are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma that causes lack of awareness to painful stimuli, sufficient to facilitate surgical applications in clinical and veterinary practice. General anaesthetics do not act as analgesics and should also not be confused with sedatives. General anaesthetics are a structurally diverse group of compounds whose mechanisms encompass multiple biological targets involved in the control of neuronal pathways. The precise workings are the subject of some debate and ongoing research.

General anesthetics elicit a state of general anesthesia. It remains somewhat controversial regarding how this state should be defined. General anesthetics, however, typically elicit several key reversible effects: immobility, analgesia, amnesia, unconsciousness, and reduced autonomic responsiveness to noxious stimuli.

Mode of administration
General anaesthetics can be administered either as gases or vapours (inhalational anaesthetics), or as injections (intravenous or even intramuscular). All of these agents share the property of being quite hydrophobic (i.e., as liquids, they are not freely miscible—or mixable—in water, and as gases they dissolve in oils better than in water). It is possible to deliver anaesthesia solely by inhalation or injection, but most commonly the two forms are combined, with an injection given to induce anaesthesia and a gas used to maintain it.

Inhalation
Inhalational anaesthetic substances are either volatile liquids or gases, and are usually delivered using an anaesthesia machine. An anaesthesia machine allows composing a mixture of oxygen, anaesthetics and ambient air, delivering it to the patient and monitoring patient and machine parameters. Liquid anaesthetics are vapourised in the machine.

Many compounds have been used for inhalation anaesthesia, but only a few are still in widespread use. Desflurane, isoflurane and sevoflurane are the most widely used volatile anaesthetics today. They are often combined with nitrous oxide. Older, less popular volatile anaesthetics include halothane, enflurane, and methoxyflurane. Researchers are also actively exploring the use of xenon as an anaesthetic.

Injection
Injectable anaesthetics are used for the induction and maintenance of a state of unconsciousness. Anaesthetists prefer to use intravenous injections, as they are faster, generally less painful and more reliable than intramuscular or subcutaneous injections. Among the most widely used drugs are: Benzodiazepines are sedatives and are used in combinations with other general anaesthetics.
 * Propofol
 * Etomidate
 * Barbiturates such as methohexital and thiopentone/thiopental
 * Benzodiazepines such as midazolam
 * Ketamine is used in the UK as "field anaesthesia", for instance in road traffic incidents or similar situations where an operation must be conducted at the scene or when there is not enough time to move to an operating room, while preferring other anaesthetics where conditions allow their use. It is more frequently used in the operative setting in the US.

Mechanism of action
Induction and maintenance of general anesthesia, and the control of the various physiological side effects is typically achieved through a combinatorial drug approach. Individual general anesthetics vary with respect to their specific physiological and cognitive effects. While general anesthesia induction may be facilitated by one general anesthetic, others may be used in parallel or subsequently to achieve and maintain the desired anesthetic state. The drug approach utilized is dependent upon the procedure and the needs of the healthcare providers.

It is postulated that general anaesthetics exert their action by the activation of inhibitory central nervous system (CNS) receptors, and the inactivation of CNS excitatory receptors. The relative roles of different receptors is still under debate, but evidence exists for particular targets being involved with certain anaesthetics and drug effects.

Below are several key targets of general anesthetics that likely mediate their effects:

GABAA receptor agonists

 * GABAA receptors are chloride channels that hyperpolarize neurons and function as inhibitory CNS receptors. General anesthetics that agonize them are typically used to induce a state of sedation and/or unconsciousness. Such drugs include propofol, etomidate, isoflurane, benzodiazepines (midazolam, lorazepam, diazepam), and barbiturates (sodium thiopental, methohexital).

NMDA receptor antagonists

 * Ketamine, an NMDA receptor antagonist, is used primarily for its analgesic effects and in an off-label capacity for its anti-depressant effects. This drug, however, also alters arousal and is often used in parallel with other general anesthetics to help maintain a state of general anesthesia. Administration of ketamine alone leads to a dissociative state, in which a patient may experience auditory and visual hallucinations. Additionally, the perception of pain is dissociated from the perception of noxious stimuli. Ketamine appears to bind preferentially to the NMDA receptors on GABAergic interneurons, which may partially explain its effects.

Two-pore potassium channels (K2Ps) activation

 * Two-pore potassium channels (K2Ps) modulate the potassium conductance that contributes to the resting membrane potential in neurons. Opening of these channels therefore facilitates a hyperpolarizing current, which reduces neuronal excitability. K2Ps have been found to be affected by general anesthetics (esp. halogenated inhalation anesthetics) and are currently under investigation as potential targets. The K2P channel family comprises six subfamilies, which includes 15 unique members. 13 of these channels (excluding TWIK-1 and TWIK-2 homomers) are affected by general anesthetics. While it has not been determined that general anesthetics bind directly to these channels, nor is it clear how these drugs affect K2P conductance, electrophysiological studies have shown that certain general anesthetics result in K2P channel activation. This drug-elicited channel activation has been shown to be dependent upon specific amino-acids within certain K2P channels (i.e. TREK-1 and TASK channels). In the case of TREK-1, activation was shown through an anesthetic perturbation to membrane lipid clusters and activation of phospholipase D2; direct binding of anesthetics to purified reconstituted TREK-1 had no effect on conductance. The effects of certain general anesthetics are less pronounced in K2P knock-out mice, as compared to their wild-type counterparts. Cumulatively, TASK-1, TASK-3, and TREK-1 are particularly well supported as playing a role in the induction of general anesthesia.

Others

 * Opioid receptor agonists are primarily utilized for their analgesic effects. These drugs, however, can also elicit sedation. This effect is mediated by opioid actions on both opioid and acetylcholine receptors. While these drugs can lead to decreased arousal, they do not elicit a loss of consciousness. For this reason, they are often used in parallel with other general anesthetics to help maintain a state of general anesthesia. Such drugs include morphine, fentanyl, hydromorphone, and remifentanil.
 * Administration of the alpha2 adrenergic receptor agonist dexmedetomidine leads to sedation that resembles non-REM sleep. It is used in parallel with other general anesthetics to help maintain a state of general anesthesia, in an off-label capacity. Notably, patients are easily aroused from this non-REM sleep state.
 * Dopamine receptor antagonists have sedative and antiemetic properties. Previously, they were used in parallel with opioids to elicit neuroleptic anesthesia (catalepsy, analgesia, and unresponsiveness). They are no longer used in the context, because patients experiencing neuroleptic anesthesia were frequently aware of the medical procedures being performed, but could not move or express emotion. Such drugs include haloperidol and droperidol.

Stages of anesthesia
During administration of an anesthetic, the receiver goes through different stages of behavior ultimately leading to unconsciousness. This process is accelerated with intravenous anesthetics, so much so that it is negligible to consider during their use. The four stages of anesthesia are described using Guedel's signs, signifying the depth of anesthesia. These stages describe effects of anesthesia mainly on cognition, muscular activity, and respiration.

Stage I: Analgesia
The receiver of the anesthesia primarily feels analgesia followed by amnesia and a sense of confusion moving into the next stage.

Stage II: Excitement
Stage II is often characterized by the receiver being delirious and confused, with severe amnesia. Irregularities in the patterns of respiration are common at this stage of anesthesia. Nausea and vomiting are also indicators of Stage II anesthesia. Struggling and panic can sometimes occur as a result of delirium.

Stage III: Surgical Anesthesia
Normal breathing resumes at the beginnings of Stage III. Nearing the end of the stage, breathing ceases completely. Indicators for stage III anesthesia include loss of the eyelash reflex as well as regular breathing. Depth of stage III anesthesia can often be gauged by eye movement and pupil size.

Stage IV: Medullary Depression
No respiration occurs in stage IV. This is shortly followed by circulatory failure and depression of the vasomotor centers. Death is common at this stage of anesthesia if no breathing and circulatory support is available.

Physiological side effects
Aside from the clinically advantageous effects of general anesthetics, there are a number of other physiological consequences mediated by this class of drug. Notably, a reduction in blood pressure can be facilitated by a variety of mechanisms, including reduced cardiac contractility and dilation of the vasculature. This drop in blood pressure may activate a reflexive increase in heart rate, due to a baroreceptor-mediated feedback mechanism. Some anesthetics, however, disrupt this reflex.

Patients under general anesthesia are at greater risk of developing hypothermia, as the aforementioned vasodilation increases the heat lost via peripheral blood flow. By and large, these drugs reduce the internal body temperature threshold at which autonomic thermoregulatory mechanisms are triggered in response to cold. (On the other hand, the threshold at which thermoregulatory mechanisms are triggered in response to heat is typically increased.)

Anesthetics typically affect respiration. Inhalational anesthetics elicit bronchodilation, an increase in respiratory rate, and reduced tidal volume. The net effect is decreased respiration, which must be managed by healthcare providers, while the patient is under general anesthesia. The reflexes that function to alleviate airway obstructions are also dampened (e.g. gag and cough). Compounded with a reduction in lower esophageal sphincter tone, which increases the frequency of regurgitation, patients are especially prone to asphyxiation while under general anesthesia. Healthcare providers closely monitor individuals under general anesthesia and utilize a number of devices, such as an endotracheal tube, to ensure patient safety.

General anesthetics also affect the chemoreceptor trigger zone and brainstem vomiting center, eliciting nausea and vomiting following treatment.

Induction
Intravenously delivered general anesthetics are typically small and highly lipophilic molecules. These characteristics facilitate their rapid preferential distribution into the brain and spinal cord, which are both highly vascularized and lipophilic. It is here where the actions of these drugs lead to general anesthesia induction.

Elimination
Following distribution into the central nervous system (CNS), the anesthetic drug then diffuses out of the CNS into the muscles and viscera, followed by adipose tissues. In patients given a single injection of drug, this redistribution results in termination of general anesthesia. Therefore, following administration of a single anesthetic bolus, duration of drug effect is dependent solely upon the redistribution kinetics.

The half-life of an anesthetic drug following a prolonged infusion, however, depends upon both drug redistribution kinetics, drug metabolism in the liver, and existing drug concentration in fat. When large quantities of an anesthetic drug have already been dissolved in the body's fat stores, this can slow its redistribution out of the brain and spinal cord, prolonging its CNS effects. For this reason, the half-lives of these infused drugs are said to be context-dependent. Generally, prolonged anesthetic drug infusions result in longer drug half-lives, slowed elimination from the brain and spinal cord, and delayed termination of general anesthesia.

Inhalational general anesthetics
Minimal alveolar concentration (MAC) is the concentration of an inhalational anesthetic in the lungs that prevents 50% of patients from responding to surgical incision. This value is used to compare the potencies of various inhalational general anesthetics and impacts the partial-pressure of the drug utilized by healthcare providers during general anesthesia induction and/or maintenance.

Induction
Induction of anesthesia is facilitated by diffusion of an inhaled anesthetic drug into the brain and spinal cord. Diffusion throughout the body proceeds until the drug's partial pressure within the various tissues is equivalent to the partial pressure of the drug within the lungs. Healthcare providers can control the rate of anesthesia induction and final tissue concentrations of the anesthetic by varying the partial pressure of the inspired anesthetic. A higher drug partial pressure in the lungs will drive diffusion more rapidly throughout the body and yield a higher maximum tissue concentration. Respiratory rate and inspiratory volume will also affect the promptness of anesthesia onset, as will the extent of pulmonary blood flow.

The partition coefficient of a gaseous drug is indicative of its relative solubility in various tissues. This metric is the relative drug concentration between two tissues, when their partial pressures are equal (gas:blood, fat:blood, etc.). Inhalational anesthetics vary widely with respect to their tissue solubilities and partition coefficients. Anesthetics that are highly soluble require many molecules of drug to raise the partial pressure within a given tissue, as opposed to minimally soluble anesthetics which require relatively few. Generally, inhalational anesthetics that are minimally soluble reach equilibrium more quickly. Inhalational anesthetics that have a high fat:blood partition coefficient, however, reach equilibrium more slowly, due to the minimal vascularization of fat tissue, which serves as a large, slowly-filling reservoir for the drug.

Elimination
Inhaled anesthetics are eliminated via expiration, following diffusion into the lungs. This process is dependent largely upon the anesthetic blood:gas partition coefficient, tissue solubility, blood flow to the lungs, and patient respiratory rate and inspiratory volume. For gases that have minimal tissue solubility, termination of anesthesia generally occurs as rapidly as the onset of anesthesia. For gases that have high tissue solubility, however, termination of anesthesia is generally context-dependent. As with intravenous anesthetic infusions, prolonged delivery of highly soluble anesthetic gases generally results in longer drug half-lives, slowed elimination from the brain and spinal cord, and delayed termination of anesthesia.

Metabolism of inhaled anesthetics is generally not a major route of drug elimination.

Ethanol
While most research focuses on the intoxicating effects of ethanol, it can also produce a general anesthesia. Since antiquity, prior to the development of modern agents, alcohol was used as a general anaesthetic.

title: General anaesthetic


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Geoffrey Chaucer

Geoffrey Chaucer (c. 1343 – 25 October 1400) was an English poet, author, and civil servant best known for The Canterbury Tales. He has been called the "father of English literature", or, alternatively, the "father of English poetry". He was the first writer to be buried in what has since come to be called Poets' Corner, in Westminster Abbey. Chaucer also gained fame as a philosopher and astronomer, composing the scientific A Treatise on the Astrolabe for his 10-year-old son, Lewis. He maintained a career in the civil service as a bureaucrat, courtier, diplomat, and member of parliament.

Among Chaucer's many other works are The Book of the Duchess, The House of Fame, The Legend of Good Women, and Troilus and Criseyde. He is seen as crucial in legitimising the literary use of Middle English when the dominant literary languages in England were still Anglo-Norman French and Latin. Chaucer's contemporary Thomas Hoccleve hailed him as "the firste fyndere of our fair langage" (i.e., the first one capable of finding poetic matter in English). Almost two thousand English words are first attested to in Chaucerian manuscripts. As scholar Bruce Holsinger has argued, charting Chaucer's life and work comes with many challenges related to the "difficult disjunction between the written record of his public and private life and the literary corpus he left behind". His recorded works and his life show many personas that are "ironic, mysterious, elusive [or] cagey" in nature, ever-changing with new discoveries.

Origin

Chaucer was born in London, most likely in the early 1340s (by some accounts, including his monument, he was born in 1343), though the precise date and location remain unknown. The Chaucer family offers an extraordinary example of upward mobility. His great-grandfather was a tavern keeper, his grandfather worked as a purveyor of wines, and his father, John Chaucer, rose to become an important wine merchant with a royal appointment. Several previous generations of Geoffrey Chaucer's family had been vintners and merchants in Ipswich. His family name is derived from the French chaucier, once thought to mean 'shoemaker', but now known to mean a maker of hose or leggings.

In 1324, his father, John Chaucer, was kidnapped by an aunt in the hope of marrying the 12-year-old to her daughter in an attempt to keep the property in Ipswich. The aunt was imprisoned and fined £250, now equivalent to about £, which suggests that the family was financially secure.

John Chaucer married Agnes Copton, who inherited properties in 1349, including 24 shops in London, from her uncle Hamo de Copton, who is described in a will dated 3 April 1354 and listed in the City Hustings Roll as "moneyer", said to be a moneyer at the Tower of London. In the City Hustings Roll 110, 5, Ric II, dated June 1380, Chaucer refers to himself as me Galfridum Chaucer, filium Johannis Chaucer, Vinetarii, Londonie, which translates as: "I, Geoffrey Chaucer, son of the vintner John Chaucer, London".

Career
While records concerning the lives of his contemporaries William Langland and the Gawain Poet are practically non-existent, since Chaucer was a public servant, his official life is very well documented, with nearly five hundred written items testifying to his career. The first of the "Chaucer Life Records" appears in 1357, in the household accounts of Elizabeth de Burgh, the Countess of Ulster, when he became the noblewoman's page through his father's connections, a common medieval form of apprenticeship for boys into knighthood or prestige appointments. The countess was married to Lionel of Antwerp, 1st Duke of Clarence, the second surviving son of the king, Edward III, and the position brought the teenage Chaucer into the close court circle, where he was to remain for the rest of his life. He also worked as a courtier, a diplomat, and a civil servant, as well as working for the king from 1389 to 1391 as Clerk of the King's Works.

In 1359, in the early stages of the Hundred Years' War, Edward III invaded France, and Chaucer travelled with Lionel of Antwerp, Elizabeth's husband, as part of the English army. In 1360, he was captured during the siege of Rheims. Edward paid £16 for his ransom, a considerable sum, and Chaucer was released.

After this, Chaucer's life is uncertain, but he seems to have travelled in France, Spain, and Flanders, possibly as a messenger and perhaps even going on a pilgrimage to Santiago de Compostela. Around 1366, Chaucer married Philippa (de) Roet. She was a lady-in-waiting to Edward III's queen, Philippa of Hainault, and a sister of Katherine Swynford, who later (c. 1396) became the third wife of John of Gaunt. It is uncertain how many children Chaucer and Philippa had, but three or four are most commonly cited. His son, Thomas Chaucer, had an illustrious career as chief butler to four kings, envoy to France, and Speaker of the House of Commons. Thomas's daughter, Alice, married the Duke of Suffolk. Thomas's great-grandson (Geoffrey's great-great-grandson), John de la Pole, Earl of Lincoln, was the heir to the throne designated by Richard III before he was deposed. Geoffrey's other children probably included Elizabeth Chaucy, a nun at Barking Abbey, Agnes, an attendant at Henry IV's coronation; and another son, Lewis Chaucer. Chaucer's "Treatise on the Astrolabe" was written for Lewis.

According to tradition, Chaucer studied law in the Inner Temple (an Inn of Court) at this time. He became a member of the royal court of Edward III as a valet de chambre, yeoman, or esquire on 20 June 1367, a position which could entail a wide variety of tasks. His wife also received a pension for court employment. He travelled abroad many times, at least some of them in his role as a valet. In 1368, he may have attended the wedding of Lionel of Antwerp to Violante Visconti, daughter of Galeazzo II Visconti, in Milan. Two other literary stars of the era were in attendance: Jean Froissart and Petrarch. Around this time, Chaucer is believed to have written The Book of the Duchess in honour of Blanche of Lancaster, the late wife of John of Gaunt, who died in 1369 of the plague.

Chaucer travelled to Picardy the next year as part of a military expedition; in 1373, he visited Genoa and Florence. Numerous scholars such as Skeat, Boitani, and Rowland suggested that, on this Italian trip, he came into contact with Petrarch or Boccaccio. They introduced him to medieval Italian poetry, the forms and stories of which he would use later. The purposes of a voyage in 1377 are mysterious, as details within the historical record conflict. Later documents suggest it was a mission, along with Jean Froissart, to arrange a marriage between the future King Richard II and a French princess, thereby ending the Hundred Years' War. If this was the purpose of their trip, they seem to have been unsuccessful, as no wedding occurred.

In 1378, Richard II sent Chaucer as an envoy (secret dispatch) to the Visconti and Sir John Hawkwood, English condottiere (mercenary leader) in Milan. It has been speculated that it was Hawkwood on whom Chaucer based his character, the Knight, in the Canterbury Tales, for a description matches that of a 14th-century condottiere.

A possible indication that his career as a writer was appreciated came when Edward III granted Chaucer "a gallon of wine daily for the rest of his life" for some unspecified task. This was an unusual grant, but given on a day of celebration, St George's Day, 1374, when artistic endeavours were traditionally rewarded, it is assumed to have been for another early poetic work. It is not known which, if any, of Chaucer's extant works prompted the reward, but the suggestion of him as a poet to a king places him as a precursor to later poets laureate. Chaucer continued to collect the liquid stipend until Richard II came to power, after which it was converted to a monetary grant on 18 April 1378.

Chaucer obtained the very substantial job of comptroller of the customs for the port of London, which he began on 8 June 1374. He must have been suited for the role as he continued in it for twelve years, a long time in such a post at that time. His life goes undocumented for much of the next ten years, but it is believed that he wrote (or began) most of his famous works during this period. Chaucer's "only surviving handwriting" dates from this period. This is a request for temporary leave from work presented to King Richard II, hitherto believed to be the work of one of his subordinates due to the low level of language.

On 16 October 1379, Thomas Staundon filed a legal action against his former servant Cecily Chaumpaigne and Chaucer, accusing Chaucer of unlawfully employing Chaumpaigne before her term of service was completed, which violated the Statute of Labourers. Though eight court documents dated between October 1379 and July 1380 survive the action, the case was never prosecuted. No details survive about Chaumpaigne's service or how she came to leave Staundon's employ for Chaucer's.

It is not known if Chaucer was in the City of London at the time of the Peasants' Revolt, but if he was, he would have seen its leaders pass almost directly under his apartment window at Aldgate.

While still working as comptroller, Chaucer appears to have moved to Kent, being appointed as one of the commissioners of peace for Kent at a time when French invasion was a possibility. He is thought to have started work on The Canterbury Tales in the early 1380s. He also became a member of parliament for Kent in 1386 and attended the 'Wonderful Parliament' that year. He appears to have been present at most of the 71 days it sat, for which he was paid £24 9s. On 15 October that year, he gave a deposition in the case of Scrope v. Grosvenor. There is no further reference after this date to Philippa, Chaucer's wife. She is presumed to have died in 1387. He survived the political upheavals caused by the Lords Appellants, despite the fact that Chaucer knew some of the men executed over the affair quite well.

On 12 July 1389, Chaucer was appointed the clerk of the king's works, a sort of foreman organising most of the king's building projects. No major works were begun during his tenure, but he did conduct repairs on Westminster Palace, St. George's Chapel, Windsor, continued building the wharf at the Tower of London and built the stands for a tournament held in 1390. It may have been a difficult job, but it paid two shillings a day, more than three times his salary as a comptroller. Chaucer was also appointed keeper of the lodge at the King's Park in Feckenham Forest in Worcestershire, which was a largely honorary appointment.

Later life
In September 1390, records say that Chaucer was robbed and possibly injured while conducting the business, and he stopped working in this capacity on 17 June 1391. He began as Deputy Forester in the royal forest of Petherton Park in North Petherton, Somerset on 22 June. This was no sinecure, with maintenance an essential part of the job, although there were many opportunities to derive profit.

Richard II granted him an annual pension of 20 pounds in 1394, and Chaucer's name fades from the historical record not long after Richard's overthrow in 1399. The last few records of his life show his pension renewed by the new king and his taking a lease on a residence within the close of Westminster Abbey on 24 December 1399. Henry IV renewed the grants assigned by Richard, but The Complaint of Chaucer to his Purse hints that the grants might not have been paid. The last mention of Chaucer is on 5 June 1400, when some debts owed to him were repaid.

Chaucer died of unknown causes on 25 October 1400, although the only evidence for this date comes from the engraving on his tomb, which was erected more than 100 years after his death. There is some speculation that he was murdered by enemies of Richard II or even on the orders of his successor Henry IV, but the case is entirely circumstantial. Chaucer was buried in Westminster Abbey in London, as was his right owing to his status as a tenant of the Abbey's close. In 1556, his remains were transferred to a more ornate tomb, making him the first writer interred in the area now known as Poets' Corner.

Relationship to John of Gaunt
Chaucer was a close friend of John of Gaunt, the wealthy Duke of Lancaster and father of Henry IV, and he served under Lancaster's patronage. Near the end of their lives, Lancaster and Chaucer became brothers-in-law when Lancaster married Katherine Swynford (de Roet) in 1396; she was the sister of Philippa (de) Roet, whom Chaucer had married in 1366.

Chaucer's The Book of the Duchess (also known as the Deeth of Blaunche the Duchesse) was written to commemorate Blanche of Lancaster, John of Gaunt's first wife. The poem refers to John and Blanche in allegory as the narrator relates the tale of "A long castel with walles white/Be Seynt Johan, on a ryche hil" (1318–1319) who is mourning grievously after the death of his love, "And goode faire White she het/That was my lady name ryght" (948–949). The phrase "long castel" is a reference to Lancaster (also called "Loncastel" and "Longcastell"), "walles white" is thought to be an oblique reference to Blanche, "Seynt Johan" was John of Gaunt's name-saint, and "ryche hil" is a reference to Richmond. These references reveal the identity of the grieving black knight of the poem as John of Gaunt, Duke of Lancaster and Earl of Richmond. "White" is the English translation of the French word "blanche", implying that the white lady was Blanche of Lancaster.

Poem Fortune
Chaucer's short poem Fortune, believed to have been written in the 1390s, is also thought to refer to Lancaster. "Chaucer as narrator" openly defies Fortune, proclaiming that he has learned who his enemies are through her tyranny and deceit, and declares "my suffisaunce" (15) and that "over himself hath the maystrye" (14).

Fortune, in turn, does not understand Chaucer's harsh words to her for she believes that she has been kind to him, claims that he does not know what she has in store for him in the future, but most importantly, "And eek thou hast thy beste frend alyve" (32, 40, 48). Chaucer retorts, "My frend maystow nat reven, blind goddesse" (50) and orders her to take away those who merely pretend to be his friends.

Fortune turns her attention to three princes whom she implores to relieve Chaucer of his pain and "Preyeth his beste frend of his noblesse/That to som beter estat he may atteyne" (78–79). The three princes are believed to represent the dukes of Lancaster, York, and Gloucester, and a portion of line 76 ("as three of you or tweyne") is thought to refer to the ordinance of 1390 which specified that no royal gift could be authorised without the consent of at least two of the three dukes.

Most conspicuous in this short poem is the number of references to Chaucer's "beste frend". Fortune states three times in her response to the plaintiff, "And also, you still have your best friend alive" (32, 40, 48); she also refers to his "beste frend" in the envoy when appealing to his "noblesse" to help Chaucer to a higher estate. The narrator makes a fifth reference when he rails at Fortune that she shall not take his friend from him.

Religious beliefs
Chaucer seems to have respected and admired Christians and to have been one himself, as he wrote in Canterbury Tales, "now I beg all those that listen to this little treatise, or read it, that if there be anything in it that pleases them, they thank our Lord Jesus Christ for it, from whom proceeds all understanding and goodness.", though he was aware that some people in the church were venal and corrupt.

Literary works
Chaucer's first major work was The Book of the Duchess, an elegy for Blanche of Lancaster, who died in 1368. Two other early works were Anelida and Arcite and The House of Fame. He wrote many of his major works in a prolific period when he worked as customs comptroller for London (1374 to 1386). His Parlement of Foules, The Legend of Good Women, and Troilus and Criseyde all date from this time. It is believed that he started The Canterbury Tales in the 1380s.

Chaucer also translated Boethius' Consolation of Philosophy and The Romance of the Rose by Guillaume de Lorris (extended by Jean de Meun). Eustache Deschamps called himself a "nettle in Chaucer's garden of poetry". In 1385, Thomas Usk made glowing mention of Chaucer, and John Gower also lauded him.

Chaucer's Treatise on the Astrolabe describes the form and use of the astrolabe in detail and is sometimes cited as the first example of technical writing in the English language. It indicates that Chaucer was versed in science in addition to his literary talents. The equatorie of the planetis is a scientific work similar to the Treatise and sometimes ascribed to Chaucer because of its language and handwriting, an identification which scholars no longer deem tenable.

Linguistic
Chaucer wrote in continental accentual-syllabic metre, a style which had developed in English literature since around the 12th century as an alternative to the alliterative Anglo-Saxon metre. Chaucer is known for metrical innovation, inventing the rhyme royal, and he was one of the first English poets to use the five-stress line, a decasyllabic cousin to the iambic pentametre, in his work, with only a few anonymous short works using it before him. The arrangement of these five-stress lines into rhyming couplets, first seen in his The Legend of Good Women, was used in much of his later work and became one of the standard poetic forms in English. His early influence as a satirist is also important, with the common humorous device, the funny accent of a regional dialect, apparently making its first appearance in The Reeve's Tale.

The poetry of Chaucer, along with other writers of the era, is credited with helping to standardise the London Dialect of the Middle English language from a combination of the Kentish and Midlands dialects. This is probably overstated; the influence of the court, chancery and bureaucracy – of which Chaucer was a part – remains a more probable influence on the development of Standard English.

Modern English is somewhat distanced from the language of Chaucer's poems owing to the effect of the Great Vowel Shift sometime after his death. This change in the pronunciation of English, still not fully understood, makes the reading of Chaucer difficult for the modern audience.

The status of the final -e in Chaucer's verse is uncertain: it seems likely that during the period of Chaucer's writing, the final -e was dropping out of colloquial English and that its use was somewhat irregular. It may have been a vestige of the Old English dative singular suffix -e attached to most nouns. Chaucer's versification suggests that the final -e is sometimes to be vocalised and sometimes to be silent; however, this remains a point on which there is disagreement. Most scholars pronounce it as a schwa when it is vocalised.

Besides the irregular spelling, much of the vocabulary is recognisable to the modern reader. Chaucer is also recorded in the Oxford English Dictionary as the first author to use many common English words in his writings. These words were probably frequently used in the language at the time, but Chaucer was the earliest extant manuscript source with his ear for common speech. Acceptable, alkali, altercation, amble, angrily, annex, annoyance, approaching, arbitration, armless, army, arrogant, arsenic, arc, artillery and aspect are just some of almost two thousand English words first attested in Chaucer.

Literary
Widespread knowledge of Chaucer's works is attested by the many poets who imitated or responded to his writing. John Lydgate was one of the earliest poets to write continuations of Chaucer's unfinished Tales. At the same time Robert Henryson's Testament of Cresseid completes the story of Cressida left unfinished in his Troilus and Criseyde. Many of the manuscripts of Chaucer's works contain material from these poets, and later appreciations by the Romantic era poets were shaped by their failure to distinguish the later "additions" from the original Chaucer.

Writers of the 17th and 18th centuries, such as John Dryden, admired Chaucer for his stories but not for his rhythm and rhyme, as few critics could then read Middle English and the text had been butchered by printers, leaving a somewhat unadmirable mess. It was not until the late 19th century that the official Chaucerian canon, accepted today, was decided upon, largely as a result of Walter William Skeat's work. Roughly seventy-five years after Chaucer's death, The Canterbury Tales was selected by William Caxton as one of the first books to be printed in England.

English
Chaucer is sometimes considered the source of the English vernacular tradition. His achievement for the language can be seen as part of a general historical trend towards the creation of a vernacular literature, after the example of Dante, in many parts of Europe. A parallel trend in Chaucer's lifetime was underway in Scotland through the work of his slightly earlier contemporary, John Barbour. Barbour's work was likely to have been even more general, as is evidenced by the example of the Pearl Poet in the north of England.

Although Chaucer's language is much closer to Modern English than the text of Beowulf, such that (unlike that of Beowulf) a Modern English speaker with an extensive vocabulary of archaic words may understand it, it differs enough that most publications modernise his idiom. The following is a sample from the prologue of The Summoner's Tale that compares Chaucer's text to a modern translation:

 * {| cellspacing="4" style="white-space: nowrap;"

 * || Original Text || Modern Translation
 * || This frere bosteth that he knoweth helle,
 * This friar boasts that he knows hell,
 * || And God it woot, that it is litel wonder;
 * And God knows that it is little wonder;
 * || Freres and feendes been but lyte asonder.
 * Friars and fiends are seldom far apart.
 * || For, pardee, ye han ofte tyme herd telle
 * For, by God, you have ofttimes heard tell
 * || How that a frere ravyshed was to helle
 * How a friar was taken to hell
 * || In spirit ones by a visioun;
 * In spirit, once by a vision;
 * || And as an angel ladde hym up and doun,
 * And as an angel led him up and down,
 * || To shewen hym the peynes that the were,
 * To show him the pains that were there,
 * || In al the place saugh he nat a frere;
 * In all the place he saw not a friar;
 * || Of oother folk he saugh ynowe in wo.
 * Of other folk he saw enough in woe.
 * || Unto this angel spak the frere tho:
 * Unto this angel spoke the friar thus:
 * || Now, sire, quod he, han freres swich a grace
 * "Now sir", said he, "Have friars such a grace
 * || That noon of hem shal come to this place?
 * That none of them come to this place?"
 * || Yis, quod this aungel, many a millioun!
 * "Yes", said the angel, "many a million!"
 * || And unto sathanas he ladde hym doun.
 * And unto Satan the angel led him down.
 * || –And now hath sathanas, –seith he, –a tayl
 * "And now Satan has", he said, "a tail,
 * || Brodder than of a carryk is the sayl.
 * Broader than a galleon's sail.
 * || Hold up thy tayl, thou sathanas!–quod he;
 * Hold up your tail, Satan!" said he.
 * || –shewe forth thyn ers, and lat the frere se
 * "Show forth your arse, and let the friar see
 * || Where is the nest of freres in this place!–
 * Where the nest of friars is in this place!"
 * || And er that half a furlong wey of space,
 * And before half a furlong of space,
 * || Right so as bees out swarmen from an hyve,
 * Just as bees swarm out from a hive,
 * ||Out of the develes ers ther gonne dryve
 * Out of the devil's arse there were driven
 * || Twenty thousand freres on a route,
 * Twenty thousand friars on a rout,
 * || And thurghout helle swarmed al aboute,
 * And throughout hell swarmed all about,
 * || And comen agayn as faste as they may gon,
 * And came again as fast as they could go,
 * || And in his ers they crepten everychon.
 * And every one crept into his arse.
 * ||He clapte his tayl agayn and lay ful stille.
 * He shut his tail again and lay very still.
 * }
 * || Where is the nest of freres in this place!–
 * Where the nest of friars is in this place!"
 * || And er that half a furlong wey of space,
 * And before half a furlong of space,
 * || Right so as bees out swarmen from an hyve,
 * Just as bees swarm out from a hive,
 * ||Out of the develes ers ther gonne dryve
 * Out of the devil's arse there were driven
 * || Twenty thousand freres on a route,
 * Twenty thousand friars on a rout,
 * || And thurghout helle swarmed al aboute,
 * And throughout hell swarmed all about,
 * || And comen agayn as faste as they may gon,
 * And came again as fast as they could go,
 * || And in his ers they crepten everychon.
 * And every one crept into his arse.
 * ||He clapte his tayl agayn and lay ful stille.
 * He shut his tail again and lay very still.
 * }
 * || And comen agayn as faste as they may gon,
 * And came again as fast as they could go,
 * || And in his ers they crepten everychon.
 * And every one crept into his arse.
 * ||He clapte his tayl agayn and lay ful stille.
 * He shut his tail again and lay very still.
 * }
 * He shut his tail again and lay very still.
 * }

Valentine's Day and romance
The first recorded association of Valentine's Day with romantic love is believed to be in Chaucer's Parlement of Foules (1382), a dream vision portraying a parliament for birds to choose their mates. Honouring the first anniversary of the engagement of fifteen-year-old King Richard II of England to fifteen-year-old Anne of Bohemia:

"For this was on seynt Volantynys day Whan euery bryd comyth there to chese his make Of euery kynde that men thinke may And that so heuge a noyse gan they make That erthe & eyr & tre & euery lake So ful was that onethe was there space For me to stonde, so ful was al the place."

Early criticism
The poet Thomas Hoccleve, who may have met Chaucer and considered him his role model, hailed Chaucer as "the firste fyndere of our fair langage". John Lydgate referred to Chaucer within his own text The Fall of Princes as the "lodesterre (guiding principle) … off our language". Around two centuries later, Sir Philip Sidney greatly praised Troilus and Criseyde in his own Defence of Poesie. During the nineteenth and early twentieth century, Chaucer came to be viewed as a symbol of the nation's poetic heritage.

In Charles Dickens' 1850 novel David Copperfield, the Victorian era author echoed Chaucer's use of Luke 23:34 from Troilus and Criseyde (Dickens held a copy in his library among other works of Chaucer), with G. K. Chesterton writing, "among the great canonical English authors, Chaucer and Dickens have the most in common."

Manuscripts and audience
The large number of surviving manuscripts of Chaucer's works is testimony to the enduring interest in his poetry prior to the arrival of the printing press. There are 83 surviving manuscripts of the Canterbury Tales (in whole or part) alone, along with sixteen of Troilus and Criseyde, including the personal copy of Henry IV. Given the ravages of time, it is likely that these surviving manuscripts represent hundreds since lost.

Chaucer's original audience was a courtly one and would have included women as well as men of the upper social classes. Yet even before his death in 1400, Chaucer's audience had begun to include members of the rising literate, middle and merchant classes. This included many Lollard sympathisers who may well have been inclined to read Chaucer as one of their own.

Lollards were particularly attracted to Chaucer's satirical writings about friars, priests, and other church officials. In 1464, John Baron, a tenant farmer in Agmondesham (Amersham in Buckinghamshire), was brought before John Chadworth, the Bishop of Lincoln, on charges of being a Lollard heretic; he confessed to owning a "boke of the Tales of Caunterburie" among other suspect volumes.

Printed editions
The first English printer, William Caxton, was responsible for the first two folio editions of The Canterbury Tales published in 1478 and 1483. Caxton's second printing, by his own account, came about because a customer complained that the printed text differed from a manuscript he knew; Caxton obligingly used the man's manuscript as his source. Both Caxton editions carry the equivalent of manuscript authority. Caxton's edition was reprinted by his successor, Wynkyn de Worde, but this edition has no independent authority. Richard Pynson, the King's Printer under Henry VIII for about twenty years, was the first to collect and sell something that resembled an edition of the collected works of Chaucer; however, in the process, he introduced five previously printed texts that are now known not to be Chaucer's. (The collection is actually three separately printed texts, or collections of texts, bound together as one volume.)

There is a likely connection between Pynson's product and William Thynne's a mere six years later. Thynne had a successful career from the 1520s until his death in 1546 as chief clerk of the kitchen of Henry VIII, one of the masters of the royal household. He spent years comparing various versions of Chaucer's works and selected 41 pieces for publication. While there were questions over the authorship of some of the material, there is no doubt that this was the first comprehensive view of Chaucer's work. The Workes of Geffray Chaucer, published in 1532, was the first edition of Chaucer's collected works. Thynne's editions of Chaucer's Works in 1532 and 1542 were the first significant contributions to the existence of a widely recognised Chaucerian canon. Thynne represents his edition as a book sponsored by and supportive of the king, who is praised in the preface by Sir Brian Tuke. Thynne's canon brought the number of apocryphal works associated with Chaucer to a total of 28, even if that was not his intention. As with Pynson, once included in the Works, pseudepigraphic texts stayed with those works, regardless of their first editor's intentions.

In the 16th and 17th centuries, Chaucer was printed more than any other English author, and he was the first author to have his works collected in comprehensive single-volume editions in which a Chaucer canon began to cohere. Some scholars contend that 16th-century editions of Chaucer's Works set the precedent for all other English authors regarding presentation, prestige and success in print. These editions certainly established Chaucer's reputation, but they also began the complicated process of reconstructing and frequently inventing Chaucer's biography and the canonical list of works which were attributed to him.

Probably the most significant aspect of the growing apocrypha is that beginning with Thynne's editions, it began to include medieval texts that made Chaucer appear as a proto-Protestant Lollard, primarily the Testament of Love and The Plowman's Tale. As "Chaucerian" works that were not considered apocryphal until the late 19th century, these medieval texts enjoyed a new life, with English Protestants carrying on the earlier Lollard project of appropriating existing texts and authors who seemed sympathetic—or malleable enough to be construed as sympathetic—to their cause. The official Chaucer of the early printed volumes of his Works was construed as a proto-Protestant as the same was done concurrently with William Langland and Piers Plowman.

The famous Plowman's Tale did not enter Thynne's Works until the second 1542 edition. Its entry was surely facilitated by Thynne's inclusion of Thomas Usk's Testament of Love in the first edition. The Testament of Love imitates, borrows from, and thus resembles Usk's contemporary, Chaucer. (Testament of Love also appears to borrow from Piers Plowman.)

Since the Testament of Love mentions its author's part in a failed plot (book 1, chapter 6), his imprisonment, and (perhaps) a recantation of (possibly Lollardism) heresy, all this was associated with Chaucer. (Usk himself was executed as a traitor in 1388.) John Foxe took this recantation of heresy as a defence of the true faith, calling Chaucer a "right Wiclevian" and (erroneously) identifying him as a schoolmate and close friend of John Wycliffe at Merton College, Oxford. (Thomas Speght is careful to highlight these facts in his editions and his "Life of Chaucer".) No other sources for the Testament of Love exist—there is only Thynne's construction of whatever manuscript sources he had.

John Stow (1525–1605) was an antiquarian and also a chronicler. His edition of Chaucer's Works in 1561 brought the apocrypha to more than 50 titles. More were added in the 17th century, and they remained as late as 1810, well after Thomas Tyrwhitt pared the canon down in his 1775 edition. The compilation and printing of Chaucer's works was, from its beginning, a political enterprise, since it was intended to establish an English national identity and history that grounded and authorised the Tudor monarchy and church. What was added to Chaucer often helped represent him favourably to Protestant England.

In his 1598 edition of the Works, Speght (probably taking cues from Foxe) made good use of Usk's account of his political intrigue and imprisonment in the Testament of Love to assemble a largely fictional "Life of Our Learned English Poet, Geffrey Chaucer". Speght's "Life" presents readers with an erstwhile radical in troubled times much like their own, a proto-Protestant who eventually came round to the king's views on religion. Speght states, "In the second year of Richard the second, the King tooke Geffrey Chaucer and his lands into his protection. The occasion wherof no doubt was some daunger and trouble whereinto he was fallen by favouring some rash attempt of the common people." Under the discussion of Chaucer's friends, namely John of Gaunt, Speght further explains:

 * Yet it seemeth that [Chaucer] was in some trouble in the daies of King Richard the second, as it may appeare in the Testament of Loue: where hee doth greatly complaine of his owne rashnesse in following the multitude, and of their hatred against him for bewraying their purpose. And in that complaint which he maketh to his empty purse, I do find a written copy, which I had of Iohn Stow (whose library hath helped many writers) wherein ten times more is adioined, then is in print. Where he maketh great lamentation for his wrongfull imprisonment, wishing death to end his daies: which in my iudgement doth greatly accord with that in the Testament of Loue. Moreouer we find it thus in Record.

Later, in "The Argument" to the Testament of Love, Speght adds:
 * Chaucer did compile this booke as a comfort to himselfe after great griefs conceiued for some rash attempts of the commons, with whome he had ioyned, and thereby was in feare to loose the fauour of his best friends.

Speght is also the source of the famous tale of Chaucer being fined for beating a Franciscan friar in Fleet Street, as well as a fictitious coat of arms and family tree. Ironically – and perhaps consciously so – an introductory, apologetic letter in Speght's edition from Francis Beaumont defends the unseemly, "low", and bawdy bits in Chaucer from an elite, classicist position.

Francis Thynne noted some of these inconsistencies in his Animadversions, insisting that Chaucer was not a commoner, and he objected to the friar-beating story. Yet Thynne himself underscores Chaucer's support for popular religious reform, associating Chaucer's views with his father William Thynne's attempts to include The Plowman's Tale and The Pilgrim's Tale in the 1532 and 1542 Works.

The myth of the Protestant Chaucer continues to have a lasting impact on a large body of Chaucerian scholarship. Though it is extremely rare for a modern scholar to suggest Chaucer supported a religious movement that did not exist until more than a century after his death, the predominance of this thinking for so many centuries left it for granted that Chaucer was at least hostile toward Catholicism. This assumption forms a large part of many critical approaches to Chaucer's works, including neo-Marxism.

Alongside Chaucer's Works, the most impressive literary monument of the period is John Foxe's Acts and Monuments.... As with the Chaucer editions, it was critically significant to English Protestant identity and included Chaucer in its project. Foxe's Chaucer both derived from and contributed to the printed editions of Chaucer's Works, particularly the pseudepigrapha. Jack Upland was first printed in Foxe's Acts and Monuments, and then it appeared in Speght's edition of Chaucer's Works.

Speght's "Life of Chaucer" echoes Foxe's own account, which is itself dependent upon the earlier editions that added the Testament of Love and The Plowman's Tale to their pages. Like Speght's Chaucer, Foxe's Chaucer was also a shrewd (or lucky) political survivor. In his 1563 edition, Foxe "thought it not out of season … to couple … some mention of Geoffrey Chaucer" with a discussion of John Colet, a possible source for John Skelton's character Colin Clout.

Probably referring to the 1542 Act for the Advancement of True Religion, Foxe said that he "'marvel[s] to consider … how the bishops, condemning and abolishing all manner of English books and treatises which might bring the people to any light of knowledge, did yet authorise the works of Chaucer to remain still and to be occupied; who, no doubt, saw into religion as much almost as even we do now, and uttereth in his works no less, and seemeth to be a right Wicklevian, or else there never was any. And that, all his works almost, if they be thoroughly advised, will testify (albeit done in mirth, and covertly); and especially the latter end of his third book of the Testament of Love … Wherein, except a man be altogether blind, he may espy him at the full: although in the same book (as in all others he useth to do), under shadows covertly, as under a visor, he suborneth truth in such sort, as both privily she may profit the godly-minded, and yet not be espied of the crafty adversary. And therefore the bishops, belike, taking his works but for jests and toys, in condemning other books, yet permitted his books to be read.'"

It is significant, too, that Foxe's discussion of Chaucer leads into his history of "The Reformation of the Church of Christ in the Time of Martin Luther" when "Printing, being opened, incontinently ministered unto the church the instruments and tools of learning and knowledge; which were good books and authors, which before lay hid and unknown. The science of printing being found, immediately followed the grace of God; which stirred up good wits aptly to conceive the light of knowledge and judgment: by which light darkness began to be espied, and ignorance to be detected; truth from error, religion from superstition, to be discerned."

Foxe downplays Chaucer's bawdy and amorous writing, insisting that it all testifies to his piety. Troubling material is deemed metaphoric, while the more forthright satire (which Foxe prefers) is taken literally.

John Urry produced the first edition of the complete works of Chaucer in a Latin font, published posthumously in 1721. According to the editors, several tales were printed, and for the first time, a biography of Chaucer, a glossary of old English words, and testimonials of author writers concerning Chaucer dating back to the 16th century. According to A. S. G Edwards, "'This was the first collected edition of Chaucer to be printed in Roman type. The life of Chaucer prefixed to the volume was the work of the Reverend John Dart, corrected and revised by Timothy Thomas. The glossary appended was also mainly compiled by Thomas. The text of Urry's edition has often been criticised by subsequent editors for its frequent conjectural emendations, mainly to make it conform to his sense of Chaucer's metre. The justice of such criticisms should not obscure his achievement. His is the first edition of Chaucer in nearly a hundred and fifty years to consult any manuscripts. Additionally, it is the first since that of William Thynne in 1534 to seek systematically to assemble a substantial number of manuscripts to establish his text. It is also the first edition to offer descriptions of the manuscripts of Chaucer's works, and the first to print texts of 'Gamelyn' and 'The Tale of Beryn', works ascribed to, but not by, Chaucer.'"

Modern scholarship
Although Chaucer's works had long been admired, serious scholarly work on his legacy did not begin until the late 18th century, when Thomas Tyrwhitt edited The Canterbury Tales, and it did not become an established academic discipline until the 19th century.

Scholars such as Frederick James Furnivall, who founded the Chaucer Society in 1868, pioneered the establishment of diplomatic editions of Chaucer's primary texts, along with careful accounts of Chaucer's language and prosody. Walter William Skeat, who, like Furnivall, was closely associated with the Oxford English Dictionary, established the base text of all of Chaucer's works with his edition, published by Oxford University Press. Later editions by John H. Fisher and Larry D. Benson offered further refinements, along with critical commentary and bibliographies.

With the textual issues largely addressed, if not resolved, attention turned to the questions of Chaucer's themes, structure, and audience. The Chaucer Research Project at the University of Chicago began in 1924. The Chaucer Review was founded in 1966 and has maintained its position as the pre-eminent journal of Chaucer studies. In 1994, literary critic Harold Bloom placed Chaucer among the greatest Western writers of all time, and in 1997 expounded on William Shakespeare's debt to the author.

List of works
The following major works are in roughly chronological order, but scholars still debate the dating of most of Chaucer's output. Works made up of a collection of stories may have been compiled over a long period.

Major works

 * The Book of the Duchess
 * The House of Fame
 * Anelida and Arcite
 * Parlement of Foules
 * Troilus and Criseyde
 * The Legend of Good Women
 * The Canterbury Tales
 * A Treatise on the Astrolabe

Translations

 * Translation of Roman de la Rose, possibly extant as The Romaunt of the Rose
 * Translation of Boethius' Consolation of Philosophy as Boece

Short poems

 * An ABC
 * Chaucers Wordes unto Adam, His Owne Scriveyn (disputed)
 * The Complaint unto Pity
 * The Complaint of Chaucer to his Purse
 * The Complaint of Mars
 * The Complaint of Venus
 * A Complaint to His Lady
 * The Former Age
 * Fortune
 * Gentilesse
 * Lak of Stedfastnesse
 * Lenvoy de Chaucer a Scogan
 * Lenvoy de Chaucer a Bukton
 * Proverbs
 * Balade to Rosemounde
 * Truth
 * Womanly Noblesse

Poems of doubtful authorship

 * Against Women Unconstant
 * A Balade of Complaint
 * Complaynt D'Amours
 * Merciles Beaute
 * The Equatorie of the Planets – A rough translation of a Latin work derived from an Arab work of the same title. It is a description of the construction and use of a planetary equatorium, which was used in calculating planetary orbits and positions (at the time, it was believed the sun orbited the Earth). The similar Treatise on the Astrolabe, not usually doubted as Chaucer's work, in addition to Chaucer's name as a gloss to the manuscript, are the main pieces of evidence for the ascription to Chaucer. However, the evidence Chaucer wrote such a work is questionable and, thus, is not included in The Riverside Chaucer. If Chaucer had not composed this work, it would have probably been written by a contemporary.

Works presumed lost

 * Of the Wreched Engendrynge of Mankynde, possible translation of Innocent III's De miseria conditionis humanae
 * Origenes upon the Maudeleyne
 * The Book of the Leoun – "The Book of the Lion" is mentioned in Chaucer's retraction. It has been speculated that it may have been a redaction of Guillaume de Machaut's 'Dit dou lyon,' a story about courtly love (a subject about which Chaucer frequently wrote).

Spurious works

 * The Pilgrim's Tale – written in the 16th century with many Chaucerian allusions
 * The Plowman's Tale or The Complaint of the Ploughman – a Lollard satire later appropriated as a Protestant text
 * Pierce the Ploughman's Crede – a Lollard satire later appropriated by Protestants
 * The Ploughman's Tale – its body is largely a version of Thomas Hoccleve's "Item de Beata Virgine"
 * "La Belle Dame Sans Merci" – frequently attributed to Chaucer, but is a translation by Richard Roos of Alain Chartier's poem
 * The Testament of Love – actually by Thomas Usk
 * Jack Upland – a Lollard satire
 * The Floure and the Leafe – a 15th-century allegory

Derived works

 * God Spede the Plough – Borrows twelve stanzas of Chaucer's Monk's Tale

In popular culture
Chaucer is one of the main characters in the 2001 film A Knight's Tale, and is portrayed by Paul Bettany.

Educational institutions

 * Chaucer Page by Harvard University, including interlinear translation of The Canterbury Tales
 * Caxton's Chaucer – complete digitised texts of Caxton's two earliest editions of The Canterbury Tales from the British Library
 * Caxton's Canterbury Tales: The British Library Copies – an online edition with complete transcriptions and images captured by the HUMI Project
 * Chaucer Metapage – project in addition to the 33rd International Congress of Medieval Studies
 * Chaucer and his works: Introduction to Chaucer and his works (descriptions of books with images, University of Glasgow Library)

title: Geoffrey Chaucer