Task: Text Categorization
Input (English): By a special case of the projection-slice theorem, performing the Hankel transform is equivalent to performing this man's transform for axially symmetric functions along with Fourier's. The absolute value of the inner product of two vectors is bounded by an inequality named for this man, who sometimes names the formula for summation by parts. The equation of titration is derived from this man's equation, which equates f(h(x)) with f(x+1), but he is better known for an identity linking the Wronskian of a second order differential equation to the equation itself and for an identity with Ruffini. Better known for proving that the general form of a quintic polynomial is insolvable, for 10 points, name this mathematician who names groups which are commutative, a Norwegian. 
Output (English): Science