Artist, born in Mendoza, Argentina. After training in Buenos Aires he moved to Paris in 1958, and helped found the Groupe de Recherche D'art Visuel with Viktor Vasarely. He became particularly interested in the exploitation of light through transparent prisms and cubes. Controversy surrounded his award of the painting prize at the 1966 Venice Biennale, and he is remembered for the Op and Kinetic art movements of the 1960s.