Zinbiel algebras are the Koszul dual of algebras named for this mathematician. This mathematician’s namesake algebra is a noncommutative generalization of Lie algebra (-5[1])for which Engel’s theorem still hold. A formula of pi named for this European mathematician is sometimes also named for Madhava, (15[1])who discovered the more general “Gregory’s series” more than a century before. An entry of a construct named for this mathematician is equal to the entry diagonally (-5[1])above (-5[3])on the left (-5[1])minus (-5[1])the entry (-5[1])to the left; (-5[2])that construct is his namesake (*) harmonic triangle. The use of the symbol (-5[1])dx to represent (10[1])an infinitesimal (10[2]-5[1])change (10[1])in x (10[2])is this (10[1])mathematician’s (10[1])namesake notation. (10[4])For 10 points, (10[1])identify this German mathematician, (10[3])whose claim of having invented calculus (10[2])was disputed by Isaac Newton. (10[2])■END■ (10[7]0[1])