Here are brief profiles of four Bolsheviks who died in the Stalin purges of the 1930s and were cleared Monday by the Soviet Supreme Court: GREGORY Y. ZINOVIEV _ Joined the Bolsheviks in 1903 and spent more than a decade in exile before returning with Lenin in 1917. He opposed Lenin on several issues during and after the revolution but was a full Politburo member and head of the Communist International until 1926. Stalin defeated Zinoviev, Lev Kamenev and Leon Trotsky for supreme power. In 1935 Zinoviev was convicted of complicity in the murder of Leningrad party chief Sergei Kirov and sentenced to 10 years in prison.The next year he was tried again and executed. LEV B. KAMENEV _ With Zinoviev, he opposed on tactical grounds the decision by Lenin to seize power in the Bolshevik Revolution. He remained a prominent party member, first joining with Zinoviev and Stalin against Trotsky and then uniting with Zinoviev and Trotsky against Stalin. He was expelled from the party several times and sentenced to five years in prison in 1935. He was retried in 1936 and executed. KARL B. RADEK _ Born in Poland, he joined Lenin's Bolsheviks in the early days. He fought in the Russian revolution and tried to organize a revolution in Germany. Radek was expelled from the Communist Party in 1927 on charges of having supported Trotsky. He was rehabilitated and allowed to help draft the 1936 constitution and edit the government newspaper Izvestia. He was convicted of treason in 1937 and is believed to have died in prison about 1940. GREGORY L. PYATAKOV _ A leader of the Ukrainian Communist Party, Pyatakov set up a government in the Russian city of Kursk under orders from Moscow and invaded the Ukraine with Red Army soldiers. He was tried with Radek as a supporter of Trotsky in 1937 and was executed.