Sum most commonly means the total of two or more numbers added together; see addition. Sum can also refer to: Mathematics Sum (category theory), the generic concept of summation in mathematics Sum, the result of summation, the addition of a sequence of numbers 3SUM, a term from computational complexity theory Band sum, a way of connecting mathematical knots Connected sum, a way of gluing manifolds Digit sum, in number theory Direct sum, a combination of algebraic objects Direct sum of groups Direct sum of modules Direct sum of permutations Direct sum of topological groups Einstein summation, a way of contracting tensor indices Empty sum, a sum with no terms Indefinite sum, the inverse of a finite difference Kronecker sum, an operation considered a kind of addition for matrices Matrix addition, in linear algebra Minkowski addition, a sum of two subsets of a vector space Power sum symmetric polynomial, in commutative algebra Prefix sum, in computing Pushout (category theory) (also called an amalgamated sum or a cocartesian square, fibered coproduct, or fibered sum), the colimit of a diagram consisting of two morphisms f : Z → X and g : Z → Y with a common domainor pushout, leading to a fibered sum in category theory QCD sum rules, in quantum field theory Riemann sum, in calculus Rule of sum, in combinatorics Subset sum problem, in cryptography Sum rule in differentiation, in calculus Sum rule in integration, in calculus Sum rule in quantum mechanics Wedge sum, a one-point union of topological spaces Whitney sum, of fiber bundles Zero-sum problem in combinatorics Computing and technology Sum (Unix), a program for generating checksums StartUp-Manager, a program to configure GRUB, GRUB2, Usplash and Splashy Sum type, a computer science term Art and entertainment Sum, the first beat (pronounced like "some") in any rhythmic cycle of Hindustani classical music "Sum", a song by Pink Floyd from The Endless River Sum: Forty Tales from the Afterlives, a 2009 collection of short stories by David Eagleman Sum 41, a Canadian punk band SUM, the computer in Goat Song (novelette) story by Poul Anderson in Magazine of Fantasy and Science Fiction, (1972). Organizations Senter for utvikling og miljø (Centre for Development and the Environment), a research institute which is part of the University of Oslo Soccer United Marketing, the for-profit marketing arm of Major League Soccer and the exclusive marketing partner of the United States Soccer Federation Society