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Japanese Communist Party

The Japanese Communist Party (日本共産党) is a communist party in Japan. Founded in 1922, it is the oldest political party in the country. It has 250,000 members making it one of the largest non-governing communist parties in the world. The party is chaired by Tomoko Tamura, who replaced longtime leader Kazuo Shii in January 2024.

The JCP was repressed by the Japanese government in the three decades immediately following its founding. The Allied occupation of Japan legalized the JCP after World War II, but the party's unexpected success in the 1949 general election led to the "Red Purge", in which the Japanese government removed tens of thousands of actual and suspected communists from their jobs. The Soviet Union encouraged the JCP to respond with a violent revolution; the consequent internal debate fractured the party into several factions. The dominant faction, backed by the Soviets, waged an unsuccessful guerrilla campaign in Japan's rural areas, which undercut the party's public support.

In 1958, Kenji Miyamoto became the JCP's leader and moderated the party's policies, abandoning the previous line of violent revolution. His efforts to regain electoral support were particularly successful in urban areas such as Osaka, Kyoto, and Tokyo, and the JCP worked with the Japan Socialist Party (JSP) in the 1970s to elect a number of progressive mayors and governors. By 1979, the JCP held about 10% of the seats in the National Diet.

Miyamoto also began distancing the JCP from the Eastern Bloc in the 1960s. The party maintained a neutral stance during the Sino-Soviet split, declared its support for multi-party democracy in opposition to the one-party politics of China and the Soviet Union, and purged pro-Soviet or Chinese members. The party saw a brief electoral resurgence after the collapse of the JSP in 1996; however, the party has generally been in decline since in terms of electoral results and party membership.

The party at present advocates the establishment of a democratic society based on scientific socialism and pacificism. It believes that this objective can be achieved by working within an electoral framework while carrying out an extra-parliamentary struggle against "imperialism and its subordinate ally, monopoly capital". As such, the JCP does not advocate violent revolution but rather a "democratic revolution" to achieve "democratic change in politics and the economy". It accepts the current constitutional position of the emperor but opposes the involvement of the Imperial House in politics. A staunchly anti-militarist party, the JCP firmly supports Article 9 of the Japanese Constitution and seeks to dissolve the Japan Self-Defense Forces. It opposes Japan's military alliance with the United States as an unequal relationship and infringement of Japan's national sovereignty.

Foundation
Sanzō Nosaka became a communist in the late 1910s and was a founding member of the Communist Party of Great Britain. Sen Katayama left Japan for the United States in 1914, after serving a prison sentence for supporting a strike. He became a communist during his time in the country and was a founding member of the Communist Party USA. Katayama founded the Association of Japanese Socialists in America and served as chair of the Far Eastern People's Congress.

In 1921, Katayama was informed by the Communist International (Comintern) that the First Congress of the Toiler of the Far East would be held on 21 January 1922 in Irkutsk. Three men from his organization (Watanabe Haruo, Taguchi Unzo, and Maniwa Suekichi) served as delegates. The Japanese Communist Party was founded in Tokyo on 15 July, at a meeting where Kyuichi Tokuda discussed sessions held between the Japanese delegation and Comintern officials. Two delegates were sent to the 4th World Congress of the Communist International and a general meeting of the party was held in Ichikawa, Chiba, on 4 February 1923.

The party's early leadership was drawn from the anarcho-syndicalist and Christian socialist movements that developed around the turn of the century. From the former came Yamakawa Hitoshi, Sakai Toshihiko, and Kanson Arahata, who had all been supporters of Kōtoku Shūsui, an anarchist executed in 1911. Katayama, another early party leader, had been a Christian socialist for much of his political life. The three former anarchists were reluctant to found the JCP, with Yamakawa shortly after arguing that Japan was not ready for a communist party and calling for work to be done solely within labor unions. Katayama's theoretical understanding of Marxism also remained low. In the aftermath of the 1923 Great Kanto Earthquake, there was a campaign of rumors instigated by Japanese state authorities that incited widespread massacres of suspected enemies of the state by military, police, and vigilante forces. Military and police officials assassinated key leftist leaders under the cover of martial law, including Ōsugi Sakae.

Outlawed and persecuted

In May 1923, a roster of the JCP's membership was found by police at Manabu Sano's quarters at Waseda University. A series of protests were occurring at the university about military training. On 5 June, almost every member of the party, except those in rural areas or outside the country, were arrested. A group of Japanese communists, including Arahata, assembled in Vladivostok in August, and decided to create a proletarian party. Those members arrested in 1923, and released in 1924 believed that the conditions for a communist party were not present and decided to dissolve the party at the Morigasaki Conference in March. However, Grigori Voitinsky rejected this and ordered them to reestablish the party. In August, a committee with Tokuda as chair was formed to reestablish the party. Masanosuke Watanabe and Sano held positions in this committee and Arahata was an organizer in the Kansai region. The JCP was formally reestablished on 4 December 1926. Fukumoto Kazuo, a rising figure in Japanese communism, was a member and his ideology, Fukumotoism, was a main part of the platform.

The JCP was outlawed in 1925 with the passage of the Peace Preservation Law, the JCP was subjected to repression and persecution by the Special Higher Police (Tokkō), nicknamed the "Thought Police". JCP members and sympathizers were imprisoned and pressured to "convert" (tenkō suru) to anti-communist nationalism. Many of those who refused to convert remained imprisoned for the duration of the Pacific War. The Japanese Communist Party member Hotsumi Ozaki, who was part of the Richard Sorge spy ring for the Kremlin, was the only Japanese person hanged for treason under the Peace Preservation Law. Police also widely used methods of torture against arrested communists. One of the JCP members killed by police torture in this period was the writer Kobayashi Takiji.

Hyōgikai was formed on 25 May 1925, and this union served as a vehicle for the communist party. Other proletariat parties (Japan Farmers Party, Japan Labour-Farmer Party, Social Democratic Party, and Labour-Farmer Party) were formed during this period. These parties won seven seats in the 1928 election, but a crackdown on 15 March resulted in 1,200 people, including Communist leaders, being arrested and the Japanese government dissolved Hyōgikai and Labour-Farmer Party. Sano, Watanabe, Shoichi Ichikawa, Kenzō Yamamoto, and Hideo Namba avoided arrested as they were serving as representatives to the 6th World Congress of the Communist International and reorganized the party. The Labour-Farmer Party was reconstituted, with opposition from the Comintern-affiliated communists, into the Proletarian Masses Party with Mosaburō Suzuki as Secretary General. An attempt to reform Hyōgikai resulted in arrests so a new organization, the National Council of Japanese Labor Unions (Zenkyō), was formed as an underground group with 5,500 members on 25 December 1928.

Police found a chart of the JCP's district organization in Tokyo after arresting a prominent member on 18 March 1929. This resulted in mass arrests that left Yamamoto, who was sick in Moscow, as one of the few leaders not in prison. 81 high-ranking members of Zenkyō were arrested in April. The party was reconstituted by Seigen Tanaka, Zenshirō Zennō, and Hiroshi Sano in July. Many members wanted to dissolve the party as the Peace Preservation Law was amended to inflict the death penalty. Jōkichi Kazama was sent from Moscow to rebuild the party in December 1930. He and Noboru Matsumura wrote the 1931 Draft Thesis, but the Comintern was displeased with it. A new document supported by the Comintern, the 1932 Draft Thesis, was written by Nosaka and served as the JCP's main document until 1946. This document stated that a bourgeois revolution to eliminate feudalism and the emperor must occur before the proletariat revolution.

Kazama and other leaders were arrested in fall 1932. The party was reformed by Masami Yamamoto, who was also sent from Moscow, in January 1933, but he was arrested in May. Manabu Sano, Kazama, Tanaka, and other imprisoned Communist leaders denounced communism starting in May. The leadership of the party's central committee passed from Eitaro Noro to Kenji Miyamoto to Hakamada Satomi as a result of each person's arrests. The party lost its organization after Satomi's arrested in 1935.

The JCP campaigned against the invasion of China and the imperial regime's expansionist policy in Asia.

Postwar reemergence
On 4 October 1945, all political prisoners, including communists that had been imprisoned for decades, were ordered to be released by the Allied military occupation of Japan. The first issue of Shimbun Akahata after the end of the war thanked the Allied occupation for the "democratic revolution" that was occurring and called for the recreation of a communist political party. A national conference was held on 8 November 1945, and the 4th Party Congress was held from 1 to 2 December.

Nosaka returned to Japan after fourteen years in exile on 10 January 1946. Under the guidance of Nosaka, the party pursued a policy of portraying itself as "lovable". Nosaka's strategy involved avoiding open calls for violent revolution and taking advantage of the seemingly pro-labor stance of the Allied occupation to organize the urban working classes and win power at the ballot box and through propaganda. In particular, the party was successful in winning acceptance of the notion that communists had been the only ones to resist Japanese wartime militarism. This propaganda effort won the party thousands of new members and an even larger number of sympathizers, especially among artists and intellectuals.

Party membership, which never exceeded 1,000 in the pre-war period, rose from 1,180 in December 1945, to 7,500 by February 1946, 70,000 by December 1947, and over 100,000 by April 1950. Sanbetsu, an union affiliated with the JCP, had around 1.5 million members as overall Japanese union membership rose to 6 million in the post-war period. The JCP benefited from Japan's Korean population that was more favorable to communism due to discrimination and high unemployment rates. The JCP made dramatic gains in the 1949 general election, tripling its popular vote support and increasing its seat total from 4 to 35.

Red Purge and turn to violence
Beginning in the fall of 1949, in reaction to the JCP's electoral success and as part of the "Reverse Course" in Allied occupation policy amid rising Cold War tensions, the Allied occupation authorities and the Japanese government carried out a sweeping Red Purge, firing tens of thousands of communists and suspected communists from government posts, teaching positions at schools, and private corporations. The purge was further intensified in response to the outbreak of the Korean War.

Douglas MacArthur considered banning the JCP on 3 May 1950. Twenty-four members of the party's central committee were removed from office on 6 June and its newspaper, Shimbun Akahata, was suspended on 27 June. A total of 11,000 workers and 1,200 government workers were fired from 1949 to 1950. Union divisions and attacks on communist influence in labor led to Sanbetsu's membership falling to 400,000 by 1949.

Against this backdrop in January 1950, the Soviet-led Cominform, at the behest of Soviet premier Joseph Stalin, issued a blistering criticism of the JCP's peaceful line as "opportunism" and "glorifying American imperialism". It also demanded that the JCP carry out an immediate violent revolution along Maoist lines. This devastating "Cominform Criticism" led rival JCP factions to compete for the Cominform's approval, and ultimately led to the militant "1951 Platform" (51年綱領) which declared that "it would be a serious mistake to think that Japan's liberation can be achieved through peaceful, democratic means" and called for an immediate violent revolution. This thesis was a combination of late Stalinist and Maoist thought. The result was a campaign of violence in which JCP activists threw Molotov cocktails at police boxes and cadres were sent up into the mountains with instructions to organize ostensibly oppressed farmers into "mountain guerrilla squads".

The backlash to the JCP's new militant line was swift and severe. Militants were rounded up, tried, and sentenced to lengthy prison terms, and in the 1952 general election, Japanese voters vented their ire at the JCP by stripping the party of every single one of its 35 Diet seats, a blow from which it would take two decades to recover. Stunned, the JCP gradually began to pull back from its militant line, a process facilitated by the death of Stalin in 1953. At the 6th Party Congress in 1955, the JCP renounced the militant line completely, returning to its old "peaceful line" of gradually pursuing socialist revolution through peaceful, democratic means.

Shigeo Shida and Ritsu Itō were informally controlling the JCP in the early 1950s. Tokuda's death in 1953 created a power vacuum in the party. Shida won and Itō was expelled from the party, having been accused of being a spy. Shida's influence waned in the late 1950s as Miyamoto, who became General Secretary in 1958, gained power. Members of Shida's faction later broke away to from a new JCP in September 1965. This group performed poorly in elections despite support from the Soviet Union.

Anpo protests

In 1960, the JCP played a central role in organizing the massive Anpo protests against the U.S.–Japan Security Treaty, which were the largest protests in Japanese history. The JCP took a different line than the Japan Socialist Party, Sohyo labor federation, and other groups who argued that the main target of the protest movement was Japanese monopoly capitalism. Instead, the JCP argued that the main enemy was American imperialism, and along with affiliated groups, focused its protests around the U.S. Embassy in Tokyo. Accordingly, JCP-linked groups were the driving force behind the "Hagerty Incident" in which the car carrying U.S. President Eisenhower's press secretary James Hagerty was mobbed outside of Tokyo's Haneda Airport on 10 June 1960, provoking a major international incident and helping to precipitate the downfall of the Nobusuke Kishi cabinet.

The Anpo protests were a turning point in the JCP's ongoing attempts to revive its political fortunes after the disastrous turn toward violent revolution in the early 1950s. Although the Maoists had been purged from the party following the earlier disaster, the JCP was still riven by the age-old rivalry between the Rōnō Ha (Worker-Farmer Faction) and the Kōza Ha (Lecture Faction), which dated back to the prewar era. Among other disagreements, the two factions disagreed over which stage of Marxist development Japan was currently in; the Rōnō Ha believed that Japan had already achieved full capitalism, which meant that an immediate socialist revolution was possible, whereas the Kōza Ha argued that Japan's transition to capitalism was not yet complete and that therefore what was needed was a "two-stage" revolutionfirst a "democratic revolution" that would overthrow American imperialism and establish true democracy, and then a "socialist revolution" that would establish communism. Although the "mainstream" of the JCP, led by Kenji Miyamoto, favored the Kōza Ha interpretation, as late as the 7th Party Congress in 1958 the "anti-mainstream" Rōnō Ha faction, led by Shōjirō Kasuga, still controlled around 40% of the delegates.

The Anpo protests greatly strengthened the hand of the Kōza Ha faction. During the protest, the JCP, still scarred by the backlash to its violent line in the 1950s, consistently advocated peaceful, orderly, and restrained protests. This stance was highly unpopular with the radical student activists of the Zengakuren student federation, who broke decisively with the JCP as a result and began to build a New Left student movement. However, the movement proved unpopular with the broader public, and the JCP was able to use its image as a "peaceful" and "positive" force during the protests as a recruitment tool. Membership in the party soared during the course of the protests, doubling from 40,000 to 80,000, and most of the new recruits wound up supporting the Kōza Ha line.

Zenith
Over the remainder of the 1960s, the Kōza Ha was able to purge many members from the Rōnō Ha faction, and others, dissatisfied with JCP policies, quit the party of their own accord. Miyamoto was able to cement his control over the party and reigned as party chairman all the way until 1982. Meanwhile, the party's membership continued to grow rapidly, and the party began to make steady gains at the ballot box, winning more and more seats in the National Diet. By the mid-1960s, the United States Department of State estimated party membership to be approximately 120,000 (0.2% of the working-age population),, Miyamoto reported a membership above 100,000 in 1964, and the party had acquired around 300,000 members by 1970.

The JCP's vote totals in the prefectural assemblies doubled between the 1959 and 1963 elections and their seats rose from 12 to 22 despite running 200 fewer candidates. The JCP's vote totals and seats in city council elections rose from 509,069 to 880,991 votes and 218 to 369 seats. Their vote totals in the town council elections doubled and their seats rose from 168 to 314.

In the 1972 general election, the JCP won an astonishing 38 seats in the Diet, surpassing its 1949 high of 35 and signaling the party's full recovery from the disastrous militant line of the early 1950s. Party membership continued to grow in the 1970s, albeit at a slower rate than in the 1960s, reaching approximately 500,000 members by 1980.

1980s to 21st century

After the dissolution of the Soviet Union, the JCP released a press statement titled "We welcome the end of a party which embodied the historical evil of great power chauvinism and hegemonism". The party also criticized the Eastern Bloc countries which abandoned socialism, describing their decisions as a "reversal of history". Consequently, the party did not suffer an internal crisis as a result of the Soviet Union's collapse in 1991, nor did it consider disbanding or changing its name. However, owing to a significant loss in electoral support, the party revised its policies in the 1990s and became a more traditional democratic socialist party.

Lam Peng Er argued in the Pacific Affairs in 1996 that "the JCP's viability is crucial to the health of Japanese democracy" because "[i]t is the only established party in parliament that has not been coopted by the conservative parties. It performs the watchdog role against the ruling parties without fear or favor. More importantly, the JCP often offers the only opposition candidate in prefectural governorship, city mayoral and other local elections. Despite the ostensible differences between the non-Communist parties at the national level, they often support a joint candidate for governor or mayor so that all parties are assured of being part of the ruling coalition. If the JCP did not offer a candidate, there would be a walkover and Japanese voters would be offered a fait accompli without an electoral avenue of protest. Promoting women candidates in elections to win women's votes is another characteristic of the party. More women are elected under the Communist label than other political parties in Japan."

In 2008, foreign media recorded an increase in support for the party due to the effect of the global financial crisis on Japanese workers. However, the party failed to increase its number of seats in the 2009 general election. Subsequently, the projected decline of the party was halted, with the JCP becoming the third-largest party in the Tokyo Metropolitan Assembly and making gains in the House of Councillors, going from six to 11 seats. The party surged in the 2014 elections, receiving 7,040,130 votes (13.3%) in the constituency section and 6,062,962 (11.37%) in the party lists.

During the nomination period of the July 2016 House of Councillors election, the party signed an agreement with the Democratic, Social Democratic and People's Life parties to field a jointly endorsed candidate in each of the 32 districts in which only one seat was contested, uniting in an attempt to take control of the House from the LDP–Komeito coalition. JCP leaders expressed willingness to enter into a coalition with the Democratic Party, a notion which was rejected by then-Democratic Party President Katsuya Okada as being "impossible" in the near future due to what he viewed as some of the "extreme leftist policies" promoted by the JCP. The party had three Councillors up for re-election and fielded a total of 56 candidates in the election, down from 63 candidates in the 2013 election, but still the second-highest number after the LDP. However, only 14 of those candidates contested single- and multi-member districts, while 42 contested the 48-seat national proportional representation block.

Councillor Tomoko Tamura was appointed as the party's first chairwoman on 18 January 2024, replacing Kazuo Shii who had occupied the role for over 23 years.

Ideology and policies
The JCP is one of the largest non-governing communist parties in the world; it is, however, politically moderate and advocates a peaceful transition to communism. Marxism–Leninism, which former party chairman Tetsuzo Fuwa had worked for years to make acceptable to the electorate, was abandoned in favor of scientific socialism in 1976. According to the Encyclopædia Britannica, the JCP became a more traditional democratic socialist party after modifying its policies in the 1990s. This analysis is supported by the Japanese political scientist Kōji Nakakita, who is often cited as a specialist on the JCP. However, unlike the Italian Communist Party, which became a social democratic party, the JCP maintains a Marxist ideology. The party sits on the left to far-left of the left–right political spectrum.

Economic policy
The JCP strives to change the nation's economic policy of what it views as serving the interests of large corporations and banks to one of "defending the interests of the people". It advocates establishing "democratic rules" that will check the activities of large corporations and "protect the lives and basic rights of the people".

Regarding the international economy, the JCP has advocated establishing a new international democratic economic order on the basis of respect for each country's economic sovereignty. The party strongly opposed Japan's consideration of the failed Trans-Pacific Partnership. The JCP views the United States, transnational corporations, and international financial capital as the main pushers of globalization, which it asserts is negatively affecting the global economy by further widening the North–South economic divide and creating irrevocable environmental problems. The JCP advocates the "democratic regulation of activities by transnational corporations and international financial capital on an international scale".

In September 2015, after the passage of the 2015 Japanese military legislation, the JCP called for cooperation from other opposition parties to form an interim government to abolish the bills. It was the first time the party had called for such cooperation with other parties.

Social policy
The JCP is generally regarded as the most progressive party in Japanese politics. The JCP has traditionally been opposed to the existence of the Imperial House since its inception. However, the party changed its stance in 2004 by acknowledging the Emperor as Japan's head of state. The JCP has stated that it supports the establishment of a democratic republic, but also that "[the monarchy's] continuation or discontinuation should be decided by the will of the majority of the people in future, when the time is ripe to do so". In 2000, the party opposed legislation which reintroduced two symbolic practices to secondary school graduation ceremonies in Japan, namely the raising of the national flag and the singing of the national anthem, both of which the party views as relics of Japan's militarist past.

LGBT rights and feminism
The JCP has been one of the political parties to vocally back LGBTQ+ rights in the country; Communist lawmakers have been working to win the passage of same-sex marriage and anti-discrimination laws in parliament. The JCP jointly supports the passing of an LGBT equality law with the Constitutional Democratic Party of Japan (CDP), the Social Democratic Party (SDP), and Reiwa Shinsengumi.

The JCP has maintained a friendly relationship with the Japanese feminist camp since its inception, and is still the most active in women's rights issues among Japan's major political parties. The JCP was the first party to call for universal suffrage for women. The party supports eliminating the wage gap between men and women and has called for the participation of more women in Japanese politics and political life.

Foreign policy
One of the JCP's main objectives is terminating the Japan–United States military alliance and the dismantling of all American military bases in Japan, with a goal to make Japan a non-aligned and neutral country, in accordance with its principles of self-determination and national sovereignty. There are about 130 American military bases and related facilities in Japan, with Okinawa Prefecture alone hosting more than half of United States Forces Japan personnel. The JCP adheres to the idea that Japan, as an Asian country, must not allow its relationship with the United States and the G8 to define its foreign relations and should put its East Asian neighbors at the center of its diplomatic efforts. It supports establishing an "independent foreign policy in the interests of the Japanese people" and rejects "uncritically following any foreign power".

The JCP advocates that Japan issue further apologies for its actions during World War II and has condemned prime ministerial visits to Yasukuni Shrine. In the 1930s, while the JCP was still illegal, it was the only political party to vocally oppose Japan's war with China. The JCP supports Japanese territorial claims over the Kuril and Senkaku Islands and Liancourt Rocks. Furthermore, the JCP has condemned North Korea's nuclear-weapons testing, calling for effective sanctions, but opposing the prospect of a military response.

The JCP's leading politicians are known to be the most active opponents of anti-Korean racism and xenophobia in Japan. Contemporary JCP politicians criticize mainstream Japanese politicians for instigating contempt towards Korea, and oppose historical revisionism in regard to Korean history and Japanese war crimes. The JCP was one of the few Japanese parties which supported the Korean independence movement. In the latter half of the 1940s, a training school for Korean revolutionaries was operated jointly by the JCP and several Korean organizations, including the Communist Party of Korea. In South Korea, the JCP is known as the only "pro-South Korea" political party in Japan. Although it is illegal to form a communist party in South Korea, Mindan maintains friendly relations with the JCP. In 2003, due to the consideration of the then liberal South Korean president Roh Moo-hyun, formal exchanges between the JCP and the South Korean government began.

Pacifism
The JCP has traditionally championed pacifism. With regards to the Japan Self-Defense Forces (Japan's armed forces), the JCP's current policy is that it is not principally opposed to its existence (in 2000 the party stated that it would agree to its use should Japan ever be attacked), but that it will seek to abolish it in the long term, international situation permitting. The JCP opposes the possession of nuclear weapons by any country, military blocs, and attempts to revise Article 9 of the Japanese Constitution, which says that "never again... [will Japan] be visited with the horrors of war through the action of government". Regarding the resolution of disputes, it argues that priority must be given to peaceful means through negotiations, not to military solutions. The JCP says that Japan must adhere to the United Nations Charter.

Sino-Soviet split
The JCP took a neutral stance during the Sino-Soviet split and Miyamoto believed that it was unnecessary for the JCP to take a side. A pro-Chinese faction under the leadership of Hakamada Satomi and pro-Soviet faction under the leadership of Yoshio Shiga and Shigeo Kamiyama existed within the JCP. However, both groups were in the minority compared to the neutral faction.

Another pro-Soviet faction of the party was under the leadership of Shōjirō Kasuga. Kasuga's faction formed the Preparatory Commission for a Socialist Reform Movement on 9 October 1961. This group broke away on 3 May 1962, and formed the Unified Socialist League with 600 members. Relations between the Soviet Union and JCP soured as the Soviets attempted to court the JSP. Shiga and Ichizo Suzuki were expelled from the party for voting in favor of the Partial Nuclear Test Ban Treaty in 1963. Shiga and Suzuki were praised in Soviet publications, including Pravda. The publication of Shimbun Akahata faced restrictions in the Soviet Union while Shiga's Voice of Japan did not.

The JCP supported China during the Sino-Indian War. Miyamoto announced the JCP's opposition to the 1968 Soviet invasion of Czechoslovakia. At the same time, the party had distanced itself from Mao and Maoism, which allowed it to avoid being associated with China's Great Leap Forward and Cultural Revolution once they started coming more fully to light in the 1970s. In July 1969, the JCP declared that if it ever came to power, it would permit the free functioning of opposition parties, in an effort to distinguish itself from the one-party states in the Soviet Union and China. A purge of pro-Chinese elements in the JCP, including Tokuda's son Nishizawa Ryūji from the Central Committee, was conducted in 1966. In 1976, mentions of "Marxism–Leninism" in the party program were changed to "scientific socialism".

In 2020, the JCP revised its platform for the first time since 2004. The new platform criticized the Chinese Communist Party, denouncing China's "great-power chauvinism and hegemonism" as "an adverse current to world peace and progress". The JCP also removed a line from its platform which described China as a country "that is beginning a new quest for socialism". JCP members have stated that this was due to human rights conditions in China. The Ministry of Foreign Affairs of China denounced the accusations of the JCP as "groundless and biased".

Organization
The party officially upholds democratic centralism. The party constitutions states decisions "shall be based on democratic discussion and finally decided by majority vote" and that "there shall be no factions or splinter groups". Along with Komeito, the JCP is unique amongst major Japanese political parties for the continuity of its leaders, with Shii having served as JCP chairman from 2000 to 2024.

Central organization
According to the party constitution, the highest body of the JCP is the Party Congress, organized by the Central Committee every 2–3 years, though it may be postponed in special circumstances. Between the congresses, the highest body is the Central Committee, elected by the Party Congress. The Central Committee meets two times every year and can also hold a plenum at the request of one-third of its membership. The Central Committee is made out of regular and alternate members; the latter can precipitate in Central Committee meetings but cannot vote. The Central Committee also elects the executive committee of the Central Committee, and its chairpersons and vice-chairpersons, the head of the Secretariat. The current chairman of the executive committee of the Central Committee of the JCP is Tomoko Tamura. The Central Committee also appoints the Disciplinary Commission and the Audit Commission, and may elect a Central Committee chairperson; the current Central Committee chair is Kazuo Shii.

The executive committee manages party affairs between Central Committee meetings. It appoints the members of the Secretariat, which manages the day-to-day affairs of the party center, and the Central Organ Paper Editors Commission. It also elects the Standing Committee of the executive committee.

Press
Shimbun Akahata (Japanese: Red Flag Newspaper) is the daily organ of the JCP in the form of a national newspaper. Musansha Shinbun (Japanese: Proletarian News) was another publication of the party which was circulated between 1925 and 1929. Several other newspapers preceded and merged into Red Flag, including Daini Musansha Shinbun (Japanese: The Second Proletarian News), which was merged into Red Flag in 1932. Daini Musansha Shinbun was itself the immediate successor to the original The Proletarian News, which was banned by the government in September 1929. Daini Musansha Shinbun began publication immediately after the ban.

In the past, the party published numerous other newspapers as well, including another national paper called Nihon Seiji Shinbun (Japanese: Japan Political News) and a theoretical journal called Zenshin (Japanese: Forward). The party also published several regional newspapers such as Class War in and around Kyoto, Osaka and Kobe, Shinetsu Red Flag in Nagano and Hokkaido News in Hokkaido. They also published numerous (the exact number is unknown) factory newspapers.

Some regional newspapers, such as Shin Kanagawa (Japanese: New Kanagawa) in Kanagawa, are still published.

Affiliated organizations
The youth wing of JCP is the Democratic Youth League of Japan. In the 1920s and 1930s, the organization published several newspapers of its own, including Rēnin Seinen (English: Lenin Youth) and Proletarian Youth.

The party also has affiliate medical and consumer co-ops. The Japanese Consumers' Co-Operative Union (JCCU), the umbrella body of the co-operative movement in Japan, has a sizable number of communists in its ranks, although the exact numbers are difficult to verify. Another example of the JCP's prevalence in the co-operative movement is the Co-op Kanagawa in the Kanagawa Prefecture, which has 800,000 members and has historical ties to the JCP. It still advertises and occasionally is published in JCP newspapers such as Red Flag and New Kanagawa. The prevalence of house unions in Japan as opposed to enterprise unions has prompted much of the exceptional development of other organizations by the JCP, as well as causing the JCP to seek other external organizational support, including from kōenkai.

The Choir of JCP-fans (JCPファン雑唱団) is a musical group which supports the JCP. Its repertory and artistic activity are strongly linked to The Singing Voice of Japan (日本のうたごえ) / うたごえ運動 ), a musical movement of Japanese working class that dates back to 1948, when the Choir of the Communist Youth League of Japan (日本青年共産同盟中央合唱団) was established. The group was founded in Kyoto in 2011 and is directed by Tadao Yamamoto, a composer, accordionist, choir director and ordinary member of the National Council of The Singing Voice of Japan. In various cultural events organized by the party, the Choir of JCP-fans appears as an element among the joined choirs of the volunteer singers of The Singing Voice of Japan. As of 2016, the choir is the only organization of Japanese musicians specializing in political support and in the cultural activity of the party.

Notable concerts and performances by the choir include:
 * 11 February 2011, Kyoto Kaikan Hall: Concert sponsored by the Kyoto Committee of the Japanese Communist Party (JCP).
 * 1 August 2013, Nishijin Bunka Center (Kyoto): Cultural Live Revolutionary Pub, in collaboration with Tokiko Nishiyama (西山登紀子), former JCP member of the House of Councilors.
 * 23 September 2014, Takaragaike Park (Kyoto): Festival Kyoto ed. 2014, organized by the Kyoto Committee of the JCP.
 * 1 February 2015, Kyoiku Bunka Center (Kyoto): Festival sponsored by the Kyoto Committee of the JCP.
 * 29 April 2016, Takaragaike Park (Kyoto): Festival Kyoto ed. 2016, organized by the Kyoto Committee of the JCP: performance with Seifuku Kōjō Iinkai (制服向上委員会) and Akira Koike (小池晃), JCP member of the House of Councilors and Secretary-General of the party.

Membership
44.09% of the JCP's membership in 1966 was between the ages of 30–39, 27.50% were below 29, 15.21% were 40–49, 8.81% were above 50, and 3.74% were of an unknown age. The most common form of employment was in factory work, civil service, education, and agrarian work. During the 1980s, party membership began to decline, falling to 500,000 by 1990 and 370,000 by 1997.

Following its advancement in the 2013 Tokyo prefectural election, the party enjoyed an increase in membership growth, with over 1,000 people joining in each of the final three months of 2013. Approximately 20% of new members during this period were aged 20 to 40, showing a higher ratio of young people joining the party than in the past. The JCP had approximately 320,000 members in January 2014.

More recently, however, membership numbers have declined, with membership around 300,000 in 2017, 270,000 in 2020, and 250,000 in 2024.

Pre-war (1922–1941)

 * Kanson Arahata
 * Sen Katayama
 * Hajime Kawakami
 * Fukumoto Kazuo
 * Takiji Kobayashi
 * Toshihiko Sakai
 * Hitoshi Yamakawa

Wartime (1941–1945)

 * Kim Chon-hae
 * Sanzō Nosaka
 * Yoshio Shiga
 * Kyuichi Tokuda

Post-war (1945–present)

 * Kiyoteru Hanada
 * Kenji Miyamoto
 * Hiromu Murakami
 * Tetsuzo Fuwa
 * Kazuo Shii
 * Hisashi Inoue
 * Takeshi Kimura

House of Representatives
Prior to 1996, the entire House of Representatives was elected by majoritarian / "semi-proportional" voting systems with votes cast for individuals (1946: limited voting in multi-member districts, 1947 to 1993 SNTV in multi-member districts). Since 1996, the House of Representatives is elected in a parallel election system—essentially two separate elections only in the lower house complicated by the fact that a candidate may stand in both segments and the sekihairitsu system which ties proportional list ranking to FPTP results: only the majority of members the House of Representatives, 295 (initially 300) seats, are elected in a majoritarian system with voting for candidates (first-past-the-post in single-member districts), while the remaining 180 (initially 200) seats are elected by a proportional representation system (votes are cast for party lists in regional multi-member districts, called "blocks" in the House of Representatives). The votes and vote percentages in the table below are the JCP candidates' vote totals for the whole election from before 1993 and just the votes for the party in the election to the 180 proportional seats after 1996.

The JCP polled 11.3% of the vote in 2000, 8.2% in 2003, 7.3% in 2005, 7.0% in 2009, and 6.2% in 2012. These results seemed to indicate a trend of declining support, but the party won 21 seats in 2014, up from eight in the previous general election, as the JCP received 7,040,130 votes (13.3%) in the constituency section and 6,062,962 (11.37%) in the party lists. This continued a new wave of support that was also evident in the 2013 Tokyo prefectural election in which the party doubled its representation. Fighting on a platform directly opposed to neoliberalism, the Trans-Pacific Partnership, attempts to rewrite the constitution, United States Forces Japan, and nuclear power, the JCP tapped into a minority current that seeks an alternative to Japan's rightward direction. Following the 2016 Japanese House of Councillors election, the party held 13 seats in the House of Councillors. After the 2017 Japanese general election, the party held 12 seats in the House of Representatives, and since the 2021 Japanese general election, it holds 10 seats.

House of Councillors
Elections to the House of Councillors are staggered. Every three years, half of the House is up for election to six-year terms. In addition, a parallel election system is used: the majority of members of the House of Councillors (currently 146 of 242, or 73 in one regular election to one half of the House) are elected in 45 (formerly 46→47) prefectural districts, votes are cast for individual candidates by SNTV, but with both multi- and single-member districts used and in the latter SNTV becomes identical to FPTP (winner-takes-all). The remaining, currently 96 members (48 per regular election) are elected in one nationwide district. Until 1980, votes there were cast for individuals too by SNTV. Since 1983, votes are cast for party lists and the seats are allocated proportionally (d'Hondt) in the nationwide district. Unlike in general elections to the lower house, a candidate may not be nominated in both segments of one regular election to the upper house. The seats totals show below are the JCP's overall post-election seat totals, not just their seats elected in that particular year. The votes shown are the votes in the election for the 48 (formerly 50) seats in the nationwide SNTV/PR segment.

House of Representatives

 * Seiken Akamine (Okinawa-1st)
 * Akira Kasai (Tokyo PR)
 * Keiji Kokuta (Kinki PR, contested Kyoto-1st)
 * Takeshi Miyamoto (Kinki PR)
 * Tōru Miyamoto (Tokyo PR, contested Tokyo-20th)

 * Nobuko Motomura (Tōkai PR)
 * Kazuo Shii (Minami-Kantō PR)
 * Tetsuya Shiokawa (Kita-Kantō PR)
 * Chizuko Takahashi (Tōhoku PR)
 * Takaaki Tamura (Kyushu PR, contested Fukuoka-10th)

House of Councillors

 * Term expires in 2025 (elected in 2019)
 * Yoshiko Kira (Tokyo at-large)
 * Gaku Ito (Saitama at-large)
 * Akiko Kurabayashi (Kyoto at-large)
 * Akira Koike (National PR)
 * Yoshiki Yamashita (National PR)
 * Satoshi Inoue (National PR)
 * Tomoko Kami (National PR)

 * Term expires in 2028 (elected in 2022)
 * Taku Yamazoe (Tokyo at-large)
 * Tomoko Tamura (National PR)
 * Sohei Nihi (National PR)
 * Tomo Iwabuchi (National PR)

title: Japanese Communist Party


text:
County of London

The County of London was a county of England from 1889 to 1965, corresponding to the area known today as Inner London. It was created as part of the general introduction of elected county government in England, by way of the Local Government Act 1888. The Act created an administrative County of London, which included within its territory the City of London. However, the City of London and the County of London formed separate ceremonial counties for "non-administrative" purposes. The local authority for the county was the London County Council (LCC), which initially performed only a limited range of functions, but gained further powers during its 76-year existence. The LCC provided very few services within the City of London, where the ancient Corporation monopolised local governance. In 1900, the lower-tier civil parishes and district boards were replaced with 28 new metropolitan boroughs. The territory of the county was 74903 acre in 1961. During its existence, there was a long-term decline in population as more residents moved into the outer suburbs; there were periodic reviews of the local government structures in the greater London area and several failed attempts to expand the boundaries of the county. In 1965, the London Government Act 1963 replaced the county with the much larger Greater London administrative area.

Geography
The county occupied an area of just under 75000 acre and lay within the London Basin. It was divided into two parts (north and south) by the River Thames, which was the most significant geographical feature. It was bordered by the River Lea with Essex to the north-east, Kent to the south-east, Surrey the south-west and Middlesex to the north. The highest point was Hampstead Heath in the north of the county at 440 ft, which is one of the highest points in London. In 1900 a number of boundary anomalies were abolished. These included the loss of the Alexandra Park exclave to Middlesex, gaining South Hornsey in return, and the transfer of Penge to Kent.

Creation of the county
The Metropolis Management Act 1855 revolutionised and amalgamated much of local government across an identical, newly formed, area. This reform created an indirectly elected Metropolitan Board of Works which initially built and maintained infrastructure for the metropolis, including modern sanitation. Over time the board gained more functions and became the de facto local authority and provider of new services for the London area. The board operated in those parts of the counties of Middlesex, Surrey and Kent that had been designated by the General Register Office as "the Metropolis" for the purposes of the Bills of Mortality. This area had been administered separately from the City of London, which came under the control of the Corporation of London.

There had been several attempts during the 19th century to reform London government, either by expanding the City of London to cover the whole of the metropolitan area; by creating a new county of London; or by creating ten municipal corporations matching the parliamentary boroughs of the metropolis. These had all been defeated in Parliament, in part because of the agency power of the City Corporation. Ultimately, the Local Government Act 1888 and the introduction of county councils in England provided the mechanism for creating a territory and authority encompassing the expanded London area. For expediency, the area of the metropolitan board was chosen for the new county, and no attempt was made to select new boundaries. This area had been out of line with the expansion of London even in 1855. For example, it anomalously omitted built-up and expanding areas such as West Ham, but included some sparsely populated areas on the metropolitan fringe.

The City of London and the County of London each formed counties for "non-administrative" purposes, with a separate Lord Lieutenant and High Sheriff for the county of London. However, the administrative county, which corresponded to the area of control of the county council, also included the City of London. In practice, the county council had very little authority over the ancient City, with some powers over drainage, roads, fire brigade, embankment of the river and flood prevention. In common with the rest of the country, the 1888 Act provided no reform of lower-tier authorities and the county was, initially at least, administered locally by a series of parish vestries and district boards.

County council
The local authority for the county was the London County Council (LCC). Initially, the LCC provided the services it had inherited from the Metropolitan Board of Works. Eventually, however, it absorbed functions from ad-hoc agencies such the London School Board and Metropolitan Asylums Board. The council was initially based in Spring Gardens, but moved to a purpose-built County Hall in the 1930s. The housing policy of the council included provision of large housing estates outside the boundaries of the county, such as that at Becontree.

Local government
In 1900, eleven years after its foundation, the London Government Act divided the County of London into 28 metropolitan boroughs. These replaced the ancient parish vestries and district boards as the second tier of local government.

County of London boroughs numbered in the information box on the right side:

† Not a metropolitan borough.

Decline in population
Population fell after World War I and as recorded at each census until its 1965 demise. In 1901, the population was 4.5 million and by 1961 it had fallen to 3.2 million. Following the 1931 census, more of the population of "Greater London" (defined at the time as the Metropolitan Police District and City of London) lived outside the county than in it. The following table illustrates the approximate population according to the census at various intervals:

†The City of London and the Metropolitan Boroughs of Bermondsey, Bethnal Green, Finsbury, Holborn, St Marylebone, St Pancras, Shoreditch, Southwark, Stepney and Westminster.

‡The Metropolitan Boroughs of Battersea, Chelsea, Islington, Kensington, Lambeth and Paddington.

§The Metropolitan Boroughs of Camberwell, Deptford, Fulham, Greenwich, Hackney, Hammersmith, Hampstead, Lewisham, Poplar, Stoke Newington, Wandsworth and Woolwich.

 * 1) Defined as the area of the Metropolitan Police district outside the County of London.

Abolition
The county of London was abolished in 1965 and was replaced by the fivefold-sized Greater London, which took in nearly all of Middlesex, along with areas in Surrey, Kent, Essex and Hertfordshire. Middlesex and Surrey had already been reduced in 1889 on the county's creation. The area "that had been" has since been known statutorily as Inner London and an Inner London Education Authority operated in the area until 1990. The 28 metropolitan boroughs were merged to form 12 new Inner London boroughs.

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

title: County of London


text:
Metropolitan Borough of Wandsworth

The Metropolitan Borough of Wandsworth was a Metropolitan borough under the London County Council, from 1900 to 1965.

History
The borough was formed from five civil parishes: Clapham, Putney, Streatham, Tooting Graveney and Wandsworth. In 1904, these five were combined into a single civil parish called Wandsworth Borough, which was conterminous with the metropolitan borough. Before 1900, these parishes, and Battersea until 1888, had been administered by the Wandsworth District Board of Works.

The borough had an irregular boundary with Mitcham in Surrey. On 1 April 1901 a small unpopulated exclave of Mitcham was transferred to Wandsworth. Part of the boundary followed the River Graveney, which had been culverted. On 1 April 1904 the boundary was straightened.

Coat of arms
The coat of arms were granted on 6 July 1901. The blue wavy division represents the Rivers Wandle and Thames. French Huguenot refugees arrived in the area in 1685, and the blue drops represent the tears of their struggle. The five stars represent the constituent former parishes. At the top is a long boat, with a dragon's head, commemorating 9th century Danish incursions along the river. The borough council's motto was We Serve.

Population and area
The borough covered 9130 acre, which made it the largest in the County of London. The population recorded in the Census was:

Constituent parishes 1801–1899 Metropolitan Borough 1900–1961

Politics
The borough was divided into nine wards for elections: Balham, Clapham North, Clapham South, Fairfield, Putney, Southfield, Springfield, Streatham, and Tooting.

Parliament constituency
For elections to Parliament, the borough was divided into one and a half constituencies: In 1918 the borough's representation was increased to five seats: In 1950 the borough's representation was reduced to four seats:
 * Clapham
 * Wandsworth
 * Balham and Tooting
 * Clapham
 * Putney
 * Streatham
 * Wandsworth Central
 * Clapham
 * Putney
 * Streatham
 * Wandsworth Central

Replacement
When the metropolitan boroughs were replaced with larger London boroughs in 1965, this borough was split. The core area of Wandsworth (about 11 km2) became part of the London Borough of Wandsworth, along with the former Metropolitan Borough of Battersea, but the areas of Streatham and Clapham (totalling 4 km2) became part of the London Borough of Lambeth.

title: Metropolitan Borough of Wandsworth


text:
SYSLINUX

The Syslinux Project is a suite of five different boot loaders for starting up Linux distros on computers. It was primarily developed by H. Peter Anvin.

Components
The Syslinux Project consists of five different boot loaders:

 * The eponymous SYSLINUX, used for booting from the FAT filesystem
 * ISOLINUX, used for booting from the ISO 9660 filesystem
 * PXELINUX, used for booting from a network server using the Preboot Execution Environment (PXE) system
 * EXTLINUX, used for booting from Btrfs, ext2, ext3, ext4, FAT, NTFS, UFS/UFS2, and XFS filesystems
 * MEMDISK, emulates a RAM disk for older operating systems like MS-DOS

The project also includes two separate menu systems and a development environment for additional modules.

SYSLINUX and ISOLINUX
SYSLINUX was originally meant for rescue floppy disks, live USBs, or other lightweight environments. ISOLINUX is meant for live CDs and Linux installation CDs.

The SYSLINUX bootloader can be used to boot multiple distributions from a single source such as a USB stick.

A minor complication is involved when booting from compact discs. The El Torito standard allows booting in two different modes:

 * No emulation – Requires storing the boot information directly on the CD. ISOLINUX is suitable for this mode.
 * Floppy emulation – Requires storing the boot information in a disk image file suitable for emulating a FAT-formatted floppy disk. SYSLINUX is suitable for this mode.

To have this choice is sometimes useful, since ISOLINUX is vulnerable to BIOS bugs. For that reason, it is handy to be able to boot using SYSLINUX. This mostly affects computers built before about 1999, and, in fact, for modern computers the "no emulation" mode is generally the more reliable method. Newer ISOLINUX versions support creation of so-called "hybrid ISO" images, that put both the El Torito boot record of the compact discs and the master boot record of hard disks into an ISO image. This hybrid image could then be written to both a compact disc or a USB flash drive.

PXELINUX
PXELINUX is used in conjunction with a PXE-compliant ROM on a network interface controller (NIC), which enables receiving a bootstrap program over the local area network. This bootstrap program loads and configures an operating system kernel that puts the user in control of the computer. Typically, PXELINUX is used for performing Linux installations from a central network server or for booting diskless workstations.

EXTLINUX
EXTLINUX is a general-purpose bootloader, similar to LILO or GRUB. Since Syslinux 4, EXTLINUX is capable of handling Btrfs, FAT, NTFS, UFS/UFS2, and XFS filesystems.

COMBOOT
SYSLINUX can be extended by COMBOOT modules written in C or assembly language. 32-bit modules typically use the  filename extension. Version 5 and later do not support 16-bit  modules.

Hardware Detection Tool (HDT)
Since the 3.74 release, the Syslinux project hosts the Hardware Detection Tool (HDT) project, licensed under the terms of GNU GPL. This tool is a 32-bit module that displays low-level information for any IA-32–compatible system. It provides both a command-line interface and a semi-graphical menu mode for browsing. HDT is also available as a bootable ISO and a 2.88 MB floppy disk image. The last update of HDT was in 2015; it has since been discontinued.

title: SYSLINUX


text:
User:Mp623

Joined on October 19, 2003.

Pages that I have either started or to which I have contributed more than just simple minor edits:

 * Akutagawa Prize
 * Flannery O'Connor Award for Short Fiction
 * Hemingway Foundation/PEN Award
 * The Hiroshima Panels
 * Hosokawa Morihiro
 * Japanese Communist Party
 * Kanda Nisshō
 * Oda Sakunosuke
 * Ōoka Shōhei
 * Tanizaki Prize
 * Tsushima Yūko
 * Yamamoto Yūzō

title: User:Mp623


text:
Talk:Continuum mechanics

Taxonomy
I disagree with the definition of continuum mechanics (at least, in concert with the continuum postulate page). As it stands, the continuum postulate definition requires both a fluid and a solid, but elasticity (physics) does not study fluids at all. So, this cannot be correct.

The common definition of continuum mechanics is that it approximates solids and fluids as continuous material (ignoring the existence of atoms). Therefore, differential equations are an appropriate mathematical method.

Support for this view on the Web is at.

I'll attempt a fix in a day or so, pending comments from others. -- hike395 15:22, 5 Nov 2003 (UTC)

I've never heard the term "solid mechanics" used, and I've done work in continuum mechanics (years ago). Rheology is also a sub-field, not a super-field of continuum mechanics. -- hike395 01:38, 8 Feb 2004 (UTC)

 * My understanding of rheology is that it embraces the deformation of materials in general, without making any assumptions about being a continuum so it could treat materials with granular structure, powders, mixtures or suspensions. I hold no brief for rheology but want to sort out the mess that is rheology, continuum mechanics, fluid mechanics (v. poor at the moment), strength of materials, elasticity and plasticity. In what ways does continuum mechanics differ from rheology if the latter is a sub-field? Cutler 01:46, 8 Feb 2004 (UTC)

 * I agree that the taxonomy for these fields in Wikipedia is poor at the moment. My memory is that papers on rheology mostly covered non-Newtonian fluids like polymers, which would make it a branch of fluid mechanics. For example, see the abstracts at . The number of people who say they study rheology seems to be smaller than the number who study fluid mechanics (who seem to call themselves "Applied Mathematicians" or "Aeronautical Engineers", anyway).

 * I've also heard "elasticity" used for both the theory of solids (what you call "solid mechanics") and, of course, for the linear stress/strain property that is well known. Maybe we should make one of the pair (Elasticity theory,Solid mechanics) be an overview of the physics of solid continua, and the other be a redirect? Then, Elasticity and Plasticity can just refer to properties of solid matter.

 * The other thing to note is that the theory of elasticity covers liquid-like materials in two ways:
 * Plastic materials that yield above a certain stress level.
 * Viscoelastic materials that have velocity-dependent internal forces.
 * So, it isn't a clean distinction, anyway.

 * Given that the taxonomy is in a mess, is there any standards body that we can appeal to that has figured this out? -- hike395 07:03, 8 Feb 2004 (UTC)

 * I agree that the rheology stuff you see in general is about non-Newtonian fluids but I think that is because all the other ground has been taken by conventional disciplines and that's all that's left to the newer discipline. However, I suspect that the ambition of the rheologists is wider and all-embracing. The definition in the article is the same as on the Society of Rheology website so I think that the words are right, it's really a discussion about usage we're having here. Prehaps we should try modifying the rheology article and see what response we get.

 * Using the term elasticity to cover elasticity and plasticity seems to me to pose some problems. What do we then call the elastic regime and how differentiate it? We could use the shear stress concept but that might be a barrier to those requiring a simple account.

 * What would work for me would be

Cutler 12:56, 8 Feb 2004 (UTC)

I think I have an idea. What is the study of all materials, regardless of state (i.e., continuous, crystalline) ? Why, materials science, of course. So, the hierarchy (on the physics/science side) could be
 * Materials science (physics of any material)
 * Crystallography
 * Solid-state physics
 * Physics of powders (etc.)
 * Continuum mechanics
 * Solid mechanics/Theory of elasticity (one is article, other is redirect)
 * Elasticity (physics)
 * Plasticity (physics)
 * Fluid mechanics/Fluid dynamics (some debate about this: one is article, other is redirect)
 * Aerodynamics (study of things that fly)
 * Computational fluid dynamics
 * Newtonian fluid mechanics
 * Rheology/Non-newtonian fluid mechanics
 * Mechanical Engineering (engineering related to materials)
 * Materials Engineering (rolling, sintering, etc.)
 * Strength of materials (engineering aspects of solid mechanics)
 * Aeronautics
 * Pneumatics
 * Hydraulics
 * Metallurgy

I think that making rheology the top-level wouldn't be consistent with common usage. In order to make the articles NPOV, however, we should mention in the text of both Materials science and rheology that rheology claims to cover any material that flows or deforms, although practically rheologist study non-Newtonian fluid mechanics.

Comments? --- hike395 05:00, 9 Feb 2004 (UTC)

 * No comments, so I went ahead and did edits for the material science & solid mechanics branch of the tree. -- hike395 06:50, 13 Feb 2004 (UTC)

 * What must be avoided is a situation where if a user looks at continuum mechanics they get one account of the world but if they look at rheology they get another and at strength of materials yet another and I've been struggling with how to make that possible. How do you feel about the table:

 * We then need to make this OK for the rheologists. The thing is, the same table needs to appear in rheology or it will look weird to the uninitiated. BTW, I have recently redone viscosity if you are interested.Cutler 11:09, 13 Feb 2004 (UTC)

 * It's OK with me. --- hike395

 * Done it - rheology. Let's see how long it lasts. Any comments? What is still missing in continuum mechanics is some indication of how far the assumption of continuity can be stretched. Does the subject embrace colloids? What are the practical limits? I don't know the answer so it would help me. Cutler 11:37, 13 Feb 2004 (UTC)

 * I don't know the answer to your questions --- I learned solid mechanics as mathematical physics. -- hike395 18:43, 14 Feb 2004 (UTC)

A 1980 author writes "constitutive equations are also required in other branches of continuum physics, such as continuum thermodynamics and continuum electrodynamics" so "continuum whatever" is a big group, anything that models matter as continuous stuff. IDave2 (talk) 15:43, 23 September 2009 (UTC)

Not a regular wiki-person, but I saw a few glaring errors in
the elasticity / continuum mechanics and related articles

1) Strength of materials is definitely NOT the same as the theory of elasticity. It is an engineering approach to solve solid mechanics problems with large contributions from people like Timoshenko in the early 20th century. The 'strength of materials' approach (almost) entirely avoids the elastic field equations and their solutions.

2) The definition of elastic material provided here is incorrect. Briefly, an elastic material is one in which the work done by external forces acting on the body is stored as (and is equal to) the Elastic Potential Energy, which is completely recoverable on unloading. Thus it is perfectly possible to have non-linear elastic materials.

3) You don't 'apply stress', you apply loads. Stress is a DEFINED quantity, as opposed to loads (forces). For example, it is convenient to define the stress as a symmetric second-rank tensor but it is possible to define an alternative, asymmetric stress (Lagrangian stress)

 * Thanks for your views. Be bold and make an edit. This whole area would benefit from a few extra informed editors. However, please note that this is an encyclodaedia so we should give a general description that it intelligible to the bright 12-year-old and then proceed to an exact definition that would be meaningful to an expert. Cutler 09:42, 18 February 2006 (UTC)

link to or section describing lagrangian vs eulerian descriptions?
I've looked around for a while, and couldn't find any article describing the Eulerian and Lagrangian descriptions of a deforming material. This leads me to suggest that either someone create such an article, or, if it exists, make its presence more obvious, or, if it is plenty obvious, please tell me where to find it. My homework grade thanks you. 128.83.69.57 02:35, 10 March 2007 (UTC)

Editions April 13 2008
I started including introductory topics of continuum mechanics. So far, sections on the concept of continuum, configuration of a continuum, and kinematics of a continuum have been included. There is still a lot more to write. Sections on conservation of mass, conservation of momentum, conservation of angular momentum, thermodynamic laws... are needed. This article should be the portal to solid mechanics and fluid mechanics. There should be a logical flow from this article to these other articles. Please review in detail what I have written, specially the equations. I think the writing also needs some improvement.--Sanpaz (talk) 04:10, 14 April 2008 (UTC)

Merger of convective derivative into continuum mechanics
Why do you (Sanpaz) want convective derivative to be merged into continuum mechanics? Crowsnest (talk) 21:23, 19 April 2008 (UTC)

 * The topic of Convective derivative does not seem to need its own article. This topic can be placed within the Continuum mechanics article and still retain all its content. Additionally, it brings the content of the article into context. However, If the Convective derivative topic needs to be expanded later then the page should be re-open. Sanpaz (talk) 23:16, 19 April 2008 (UTC)

 * As far as I am concerned: go ahead. However, it is important that people can find "convective derivative", if they search for it. So I would suggest that in the case of a merger, convective derivative becomes a redirect to the appropriate article or section. Crowsnest (talk) 07:18, 21 April 2008 (UTC)
 * Please note there are many redirects to here, e.g. advective derivative, substantive derivative, substantial derivative, material derivative, Lagrangian derivative, Stokes derivative and particle derivative. Crowsnest (talk) 11:40, 22 April 2008 (UTC)

I'm against this. I think the topic deserves it's own article; it's a big enough concept. — Ben pcc (talk) 22:41, 10 May 2008 (UTC)
 * Ok, I will take the merging label off Sanpaz (talk) 23:09, 10 May 2008 (UTC)

The name of the article
To me the name Continuum mechanics doesn't make any sense and wander why not something like Mechanics of continuous media or even something better. --Gulmammad (talk) 16:04, 20 May 2008 (UTC)

 * Continuum mechanics is a well established term. For instance Google Books gives over 800 results when searching on "continuum mechanics" in the book title, and Google Scholar over 2000 articles with the exact phrase in the title. Further, in my view, the name makes sense: just like particle mechanics describes the mechanics of particles, continuum mechanics describes the mechanics of a continuum. Crowsnest (talk) 21:17, 20 May 2008 (UTC)
 * Actually in above I meant Continuous instead of Continuum. And what I was wandering at was those results of Google, almost no-one uses "my version" of the name, while one of the Landau edition books, vol. 8, has similar name, Electrodynamics of Continuous Media. --Gulmammad (talk) 21:36, 22 May 2008 (UTC)
 * Continuous media already redirects here. Perhaps Mechanics of continuous media is another good redirect to add, and include this phrase in the head of the article. I would leave the name of the article as it is now. – Crowsnest (talk) 21:56, 22 May 2008 (UTC)

Empty Space
While most believe that matter is a bundle of energy separated by empty space, this is not true. There is no empty space in the universe. All space where matter doesn't exist is permeated by fields: electromagnetic and gravitational to say the least. It is the fundamental essence of space that permits matter to exist. Thought experiment time: close a box and draw a perfect vacuum. Remove all matter and then all energy and fields from it. What are the physical properties of the inside of this box? It has no mass, no fields, no energy. This is the definition of nothing, yet when you open the box the universe fills it right back up. Nothing has the ability to support matter and energy. This is in itself a physical property and therefore the space is not empty. It is potential. —Preceding unsigned comment added by 75.70.62.142 (talk) 16:09, 30 December 2008 (UTC)

Question of 'b'
Hi all, I'm wondering if we can remove the coordinate system vector 'b' from this introductory page. It is only used once, which usually leaves me wondering "where did this come from?", and is promptly dispensed with after being mentioned. I am browsing four CM books and only one (Chung) explicitly mentions a warped coordinate system traveling with the particle. I see that such an approach introduces (in addition to 'b') three more axis vectors and lets one write some expressions with a vector-type notation rather than summation or matrix notation, but it is not required to obtain the important CM operators like Jacobian, stress and rate of change of strain tensors, and so on, and I think the article would be less cluttered and better as an intro if we (quietly) don't mention 'b' and its (optional) coordinate system. Thoughts? IDave2 (talk) 20:40, 26 September 2009 (UTC)

Question of mass balance
I would guess that solid mechanicians don't expect new steel to "flow into" their steel bars but, if it did, then wouldn't this invalidate the Jacobian assumption? For example, if some new oil just flowed into my deformed body (gross!) then there is no (inverse) mapping relating it to the reference body (because it does not exist in the reference body) so we can no longer use J or F like before? IDave2 (talk) 21:35, 26 September 2009 (UTC)

 * IDave2: Two of the principal assumptions in the classical presentations of CM are, for a given "body", (1) the set of material points is fixed, and (2) mass is (globally) conserved. Of course, these assumptions can be relaxed, but doing so adds significant complication to the (classical) results, e.g., non-constant reference densities, or strong discontinuities in the solutions.  I have done a fair bit of work on this, and could add some text if desired by anyone here . . . Anonymous

Physicists have very little to do with Continuum Mechanics
I believe it is not reasonable to consider Continuum Mechanics a branch of physics. Only a tiny proportion of research into continuum mechanics over the last 60 years or so has been performed by physicists - (a notable exception being magnetohydrodynamics, because of its importance for the study of plasmas in stars & planets). Most "famous" physics departments (at least in the US) have almost no one working in continuum mechanics. The theoretical work is done by applied mathematicians and practical work by engineers. Very few physicists sit on the editorial boards of mechanics journals. I think it is reasonable to say that physicists have no more than an elementary understanding of the behavior of deformable continua - an average physicist's idea of "mechanics" (at the mesoscale) begins and ends with rigid bodies and "potential" fluid flows.

The reasons for this are interesting and multi-fold - the explosive, "headline grabbing" developments in atomic and modern physics in the 20th century being one of them. At any rate, I don't think it should be classified as a branch of physics any more. Commutator (talk) 07:30, 18 October 2009 (UTC)
 * You just stated an opinion, with no reference. Continuum Mechanics is a branch of physics that uses a mathematical theory (continuum theory). Whether physicists, engineers, or mathematicians use it more or not at all is another issue, which does not take away the fact that it is a theory to interpret the physical world. Please read Continuum Mechanics by Irgens page 2, and also Continuum Mechanics by Ellis Harold Dill pages 1 and 2. sanpaz (talk) 02:16, 19 October 2009 (UTC)
 * Hi Sanpaz, would you object to a sentence in the article stating that most of the research in continuum mechanics is not performed by physicists? In the sense you describe it, it is physics, but it is certainly an area of physics neglected by physicists. Truesdell says something to this effect in pages 8 & 9  of his book (Nonlinear-field theories of mechanics), I'll try to dig up more modern references about it.Commutator (talk) 13:25, 19 October 2009 (UTC)
 * I think it would be something good to state in the article with Truesdell as the reference. However, it would be good to have a more recent reference (if you could find one) that states that currently research into continuum mechanics is rarely done by physicists. sanpaz (talk) 14:55, 19 October 2009 (UTC)

An effort to improve the continuum mechanics area
Hi, I've just edited the lead in a way in which I hope is helpful, aiming to make it slightly more accessible in the first instance, but keep some of the detail that was there. I'm keen to help out in improving the whole of this branch of Wikipedia, so I'd be interested to see if there is anyone out there watching these articles who I can ask for guidance/advice? Thudso (talk) 23:12, 10 December 2009 (UTC)
 * Hi Thudso, I am also interest in this topic and have worked on this and other pages related to Continuum Mechanics (stress (mechanics), Deformation (mechanics), Infinitesimal strain theory and Finite strain theory. I saw your changes and I think they were good. I'll be around if you want to discuss about these topics. If you feel something needs to change do it and explain why and usually if people agree it will stand. If people disagree then a discussion about the change happens. At least that is my approach. Sometimes is better to say what you want to change and then ask for input (if the change is too big). Apart from that enjoy editing. All these pages on continuum mechanics sure need more working hands like yours. sanpaz (talk) 00:40, 11 December 2009 (UTC)

 * I have edited the first paragraph after the ToC. I looked up the "Hill-Mandel condition" described, and found that Ostaja-Starzewski cites only books from the 1960s which use this term, but sources up to the present day referring to the "Hill condition". I therefore changed "Hill-Mandel" to "Hill", see P.245 in Ostoja-Starzewski for details. I was wondering if Hill condition need a separate article? Probably a little overkill at the moment, since what we already have needs improving first, but at some point in the future, I hope! Having read through the next paragraph, I think the two need to be merged, I might get some time to spend on this a little bit later. Thudso (talk) 16:50, 11 December 2009 (UTC)

 * Just been working on the second paragraph. I noticed that most of the original work there is yours, Sanpaz. I was wondering what the difference between $$\ \kappa_t$$ and $$\ \chi$$ that is introduced further down the page is? Thudso (talk) 22:30, 11 December 2009 (UTC)
 * $$\ \kappa_t$$ and $$\ \chi$$ are both mapping functions. I just realized I made a mistake (I don't know why I wrote it the way I did). The first function should have a symbol X to identify the particle, which gives the position vector $$\ \mathbf x =\kappa_t(X)$$, thus mapping the configuration of the body. The second mapping function maps the current configuration to the reference configuration, so it has a position vector $$\mathbf X$$ as the input. Check the book by Mase 1999. I need to correct that and write the reference. sanpaz (talk) 23:37, 14 December 2009 (UTC)

Lagrangian balance of momentum
The balance of momentum expressed in the article in the reference configuration, using the transpose of the first-Piola Kirchhoff stress tensor looks WRONG. It seems to me that the equation should be the same, but using the first-Piola Kirchhoff stress tensor itself and not its transpose.

Reference : Marsden, J., & Hughes, T. (1994). Mathematical foundations of elasticity.

Could anyone confirm or infirm ?

 * Quoting Belytschko, Liu, Moran (Nonlinear Finite Elements for Continua and Structures), p. 105 : "The definition of the nominal stress P is similar to that of the Cauchy stress ... The nomenclature used by different authors for nominal stress and first Pioal-Kirchhoff stress is contradictory. Truesdell and Noll (1965), Ogden (1984), and Marsden and Hughes (1983) use the definition given here, whereas Malvern (1969) calls P the first Piola-Kirchhoff stress."  In the wikipedia article N is the nominal stress and P is the 1st PK stress. The Truesdell-Noll definition is used.  Bbanerje (talk) 22:50, 22 September 2014 (UTC)

Granular mechanics
Does granular mechanics fall under the general heading of continuum mechanics? It's part of the continuum mechanics group here at DAMTP, but I don't know whether that's anomalous or not (Cambridge can be anomalous sometimes). --jftsang 09:01, 15 June 2015 (UTC)

 * I would say yes granular mechanics does belong here (but I would say that as I am an old Cambridge graduate). My reasons are that a lot of granular modelling is at the continuous PDE level, and that the underlying physical system of granular material is a mechanical system.  To indicate where I think the limits of discourse would lie, recall that any problem studying probability density functions as a functions of space-time would be termed a "continuum" field of study.  However, for example, I would exclude fields such as neuroscience because although many neuroscience models are continuum PDEs, the underlying mechanisms are that of the firing of neurons.  Yes, at an even lower level a neuron is a mechanical device (probably), but at the functional level of current neuroscience it is not.  So I suggest brain waves etc are outside "continuum mechanics" (at least currently). --twbaroberts
 * The mechanics of a system of deformable grains == continuum mechanics with contact and jump conditions. If the grains are rigid, one doesn't need the complications of the continuum assumption and granular mechanics is just rigid body dynamics with contact and impact.  Large volumes of sand (and other cohesionless materials) can be modeled as continua but there are some phenomena that (so far) cannot be reproduced with standard (local) continuum mechanics and need non-local approaches. Bbanerje (talk) 20:36, 17 June 2015 (UTC)

I think there is a mistake in the balance laws, can someone confirm?
If we use the definitions

$$ { \begin{align} P_{ij} &= J \sigma_{ik} F^{-1}_{jk} \;, \\ F_{ij} &= \frac{\partial x_i}{\partial X_j} \;, \\ F^{-1}_{ij} &= \frac{\partial X_i}{\partial x_j} \;, \\ L_{ij} &= \frac{\partial v_i}{\partial x_j} \;, \\ \dot{F}_{ij} &= L_{ik} F_{kj} \;, \; , \\ J &= \text{det} \boldsymbol{F} \;, \; , \\ \end{align} } $$

then we get

$$ { J \boldsymbol{\sigma} : \boldsymbol{L} = J \sigma_{il} L_{il} = J \sigma_{il} \delta_{ml} L_{im} = J \sigma_{il} F_{mj} F^{-1}_{jl} L_{im} = J \sigma_{il} F^{-1}_{jl} L_{im} F_{mj} = P_{ij} \dot{F}_{ij} = \boldsymbol{P} : \dot{\boldsymbol{F}} \; , } $$

which does not fit with the energy conservation law in the Lagrangian frame given by this page, which has the transposed of $$\boldsymbol{P}$$. The same problem could be shown for the momentum equation.

I think that the equations, which are currently,

$$   {    \begin{align} \rho_0~\ddot{\mathbf{x}} - \boldsymbol{\nabla}_{\circ}\cdot\boldsymbol{P}^T -\rho_0~\mathbf{b} & = 0 \;, \\ \rho_0~\dot{e} - \boldsymbol{P}^T:\dot{\boldsymbol{F}} + \boldsymbol{\nabla}_{\circ}\cdot\mathbf{q} - \rho_0~s & = 0 \;, \\ \rho_0~\ddot{\mathbf{x}} - \boldsymbol{\nabla}_{\circ}\cdot\boldsymbol{N} -\rho_0~\mathbf{b} & = 0 \;, \\ \rho_0~\dot{e} - \boldsymbol{N}:\dot{\boldsymbol{F}} + \boldsymbol{\nabla}_{\circ}\cdot\mathbf{q} - \rho_0~s & = 0 \;, \\ \end{align} } $$

should be replaced by

$$   {    \begin{align} \rho_0~\ddot{\mathbf{x}} - \boldsymbol{\nabla}_{\circ}\cdot\boldsymbol{P} -\rho_0~\mathbf{b} & = 0 \;, \\ \rho_0~\dot{e} - \boldsymbol{P}:\dot{\boldsymbol{F}} + \boldsymbol{\nabla}_{\circ}\cdot\mathbf{q} - \rho_0~s & = 0 \;, \\ \rho_0~\ddot{\mathbf{x}} - \boldsymbol{\nabla}_{\circ}\cdot\boldsymbol{N}^T -\rho_0~\mathbf{b} & = 0 \;, \\ \rho_0~\dot{e} - \boldsymbol{N}^T:\dot{\boldsymbol{F}} + \boldsymbol{\nabla}_{\circ}\cdot\mathbf{q} - \rho_0~s & = 0 \;. \\   \end{align} } $$

Can someone confirm this?

I think different heat flux vectors $$\boldsymbol{q}$$ should also be used for Lagrangian and Eulerian formulations! — Preceding unsigned comment added by DeNayGo (talk • contribs) 11:26, 12 January 2017 (UTC)

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Concept of a continuum
In the section Concept of a continuum, the following three paragraphs deal with criteria for application of the continuum assumption. These paragraphs are not essential to the article since they do not discuss or explain the continuum concept itself but rather raise possible questions about its validity and its application. For an article which tries to explain a fundamental idea whose basic concept is not excessively difficult to grasp, these paragraphs are too detailed, and I suggest they should be removed. Alternatively – if other editors feel these paragraphs are truly important – they might be moved to the end of the article as a new section.

Here are the three paragraphs:

The validity of the continuum assumption may be verified by a theoretical analysis, in which either some clear periodicity is identified or statistical homogeneity and ergodicity of the microstructure exists. More specifically, the continuum hypothesis/assumption hinges on the concepts of a representative elementary volume and separation of scales based on the Hill–Mandel condition. This condition provides a link between an experimentalist's and a theoretician's viewpoint on constitutive equations (linear and nonlinear elastic/inelastic or coupled fields) as well as a way of spatial and statistical averaging of the microstructure.[1]

When the separation of scales does not hold, or when one wants to establish a continuum of a finer resolution than that of the representative volume element (RVE) size, one employs a statistical volume element (SVE), which, in turn, leads to random continuum fields. The latter then provide a micromechanics basis for stochastic finite elements (SFE). The levels of SVE and RVE link continuum mechanics to statistical mechanics. The RVE may be assessed only in a limited way via experimental testing: when the constitutive response becomes spatially homogeneous.

Specifically for fluids, the Knudsen number is used to assess to what extent the approximation of continuity can be made.

I prefer not to remove these paragraphs myself as I am not qualified in this field. I hope someone with more knowledge will consider doing so. Dratman (talk) 18:04, 17 March 2019 (UTC)

 * Moved, also rewrote that section. Still feels like there might be some redundancy between "Explanation" and "Concept of a continuum" sections. Also the validity section could really do with more citations but I haven't looked into that much yet. Adigitoleo (talk) 10:59, 28 December 2022 (UTC)

Edit to explanation section
Hello, for those interested I have just edited the explanation section. Minor rephrasing and more links, see the diff here https://en.wikipedia.org/w/index.php?title=Continuum_mechanics&diff=1130035568&oldid=1126094519 Adigitoleo (talk) 08:54, 28 December 2022 (UTC)

 * I have made further edits to the "concepts of a continuum" section and split off a new section "validity" which ironically lacks citations that I can't provide at the moment. Adigitoleo (talk) 11:01, 28 December 2022 (UTC)

Removal of car traffic example
I would suggest removing/replacing the car traffic example. I made some small edits for conciseness, but have left it in at the moment. However, I don't think the example is a great fit for the following reasons:

 * This is not a textbook: I'm not convinced that an example belongs in this article, the space could be used for expanding the section on "validity" or creating a section on volume elements (perhaps bringing in the small and lonely Volume element article, unless that is better suited to a finite element article?)
 * This is not a PDE article. The example might be better suited in a mathematics article?
 * The article focuses on continuous media and approximating the traffic on a highway as a continuum is perhaps not the most intuitive example, because cars are quite obviously discrete even in a macroscopic sense. It is also out of place coming before continuum mechanics (which is focused on bodies in 3D space).

For now I think I will move the example down further, if there are no objections I will remove it in the next month. Adigitoleo (talk) 11:45, 28 December 2022 (UTC)

 * Car traffic example removed 08/02/2023 Adigitoleo (talk) 07:16, 8 February 2023 (UTC)

title: Talk:Continuum mechanics