One mathematician with this last name developed an algebra in which the most general associativity relations are x and y x times y equals y times x and quantity x-squared times y, close quantity times x equals x-squared times quantity y times x. Another mathematician with this last name proved the theorem that a simple, closed curve divides the plain disjoint interior and exterior regions; such curves also bear his name. Still another mathematician with this last is the 
One mathematician with this last name developed an algebra in which the most general associativity relations are x and y x times y equals y times x and quantity x-squared times y, close quantity times x equals x-squared times quantity y times x. Another mathematician with this last name proved the theorem that a simple, closed curve divides the plain disjoint interior and exterior regions; such curves also bear his name. Still another mathematician with this last is the second namesake of a method in which a matrix is inverted by reducing it reduced row-echelon form. For 10 points, give this last name of mathematician Wilhelm, who names a form of matrix elimination with Carl Friedrich Gauss.
One mathematician with this last name developed an algebra in which the most general associativity relations are x and y x
{Jordan}