More generally, the solution set to an arbitrary collection "E" of relations ("E") ("i" varying in some index set "I") for a collection of unknowns formula_7, supposed to take values in respective spaces formula_8, is the set "S" of all solutions to the relations "E", where a solution formula_9 is a family of values formula_10 such that substituting formula_7 by formula_9 in the collection "E" makes all relations "true".