formal sum

An expression which looks like a sum but where the symbol + has a purely symbolic role, in the sense that the summands cannot be meaningfully combined.

An element of a free abelian group or vector space regarded as a sum of basis elements.

An expression which looks like a sum but where the symbol + has a purely symbolic role, in the sense that the summands cannot be meaningfully combined.

A sum of an infinite sequence of numbers considered as an indeterminate object, in the sense of being subject to certain algebraic manipulations but not necessarily convergent.