French-American mathematician who in 1984 proved the Bieberbach conjecture. This conjecture, posed by German mathematician Ludwig Bieberbach in 1916, dealt with properties of maps, specifically with mapping the surface of one shape onto another. One example of this procedure is the mapping of Earth's spherical surface onto a flat map. De Branges was able to show that transferring maps from generalized mathematical surfaces onto others was topologically possible provided that certain mathematical conditions were met.