John Hamal Hubbard was born on October 6 or 7, 1945 (the actual date is unknown). He is an American mathematician who is currently a professor at Cornell University and the Université de Provence. He is well known for the mathematical contributions he made with Adrien Douady in the field of complex dynamics, including a study of the Mandelbrot set. One of their most important results is that the Mandelbrot set is connected.Hubbard graduated with a Doctorat d'État from Université de Paris-Sud in 1973 under the direction of Adrien Douady; his thesis was entitled Sur Les Sections Analytiques de La Courbe Universelle de Teichmüller and was published by the American Mathematical Society.