José Luis Massera

José Luis Massera (Genoa, Italy, June 8, 1915 – Montevideo, September 9, 2002) was a Uruguayan mathematician who researched the stability of differential equations.

Massera's lemma is named after him. He published over 40 papers during 1940–1970. A militant Communist, he was a political prisoner during 1975–1984. In the 1930s, Julio Rey Pastor gave regular weekend lectures on topology in Montevideo to a group that included Massera. Stimulated by contact with Argentine mathematics, the 1950s saw Uruguay develop a fine school in mathematics, of which Massera was very much a part.

Massera developed new notions of stability, and published several foundational papers and an influential textbook. His results in (Massera 1950) on periodic differential equations have been heavily cited and are referred to as Massera's theorem. His work in (Massera 1949) and (Massera 1956) on the converse to Lyapunov's criterion is also influential, and contain the well known Massera's lemma. His textbook (Massera & Schäffer 1966) is also heavily cited.

After military intervention in Uruguay in 1973, Massera was arrested on October 22, 1975 in Montevideo and was held in solitary confinement for nearly a year. During this time he was subjected to repeated torture resulting in injuries including a fractured pelvis. In October 1976 he was taken from solitary confinement, tried and convicted for "subversive association", and given a 24-year prison sentence. On June 22, 1979, as a consequence of a proposal put forward by Gaetano Fichera and unanimously approved by the whole Mathematics Faculty Council of the Sapienza University of Rome, he was awarded the laurea honoris causa while still being under conviction. He was released in 1984.