In spite of his somewhat fragmented education (he never completed a formal doctoral program), Stefan Banach made important contributions to a number of fields of mathematics, including the theory of orthogonal series, topology, the theory of measure and integration, set theory, and the theory of linear spaces of an infinite number of dimensions. He is probably best remembered, however, for his work on functional analysis.

Stefan Banach was born on March 30, 1892, in Kraków, Poland. His father was named Greczek, a railway official from peasant background. He and Stefan's mother (whose name has been lost) abandoned their young child to a laundress almost immediately after his birth. The child took on his foster mother's surname of Banach, but almost nothing else is known about his early childhood. Banach apparently developed an interest in mathematics at an early age and taught himself the fundamentals of the subject. By...