Mandelbrot, Benoit B., 1924-, French mathematician, b. Warsaw, Poland. Largely self-taught and considered a maverick in the field of mathematics, he is uncomfortable with the rigorously pure logical analysis prescribed by Nicolas Bourbaki and relies instead on his talent for visualizing natural phenomena. A pioneer of chaos theory, he conceived, developed, and applied fractal geometry, which is used to find order in apparently erratic shapes and processes.