FTP, name this G  erman mathematician, a topologist best remembered for the description, discovered in his papers after his death, of a one-sided surface named for him.
In 1816, he became professor of astronomy at Leipzig, a position he would hold for the rest of his career. In a lecture of 1840, he proposed the four- color problem, though he was better known as a developer of barycentric calculus. FTP, name this G  erman mathematician, a topologist best remembered for the description, discovered in his papers after his death, of a one-sided surface named for him.
In 1816, he became professor of astronomy at Leipzig, a position he would hold for the rest of his career.
August Mobius