Hayaan nating ang Padron : Mvar ay maging katipunang arbitraryo at hayaan natimg ang F ( X , R ) { \ displaystyle { \ mathcal { F } } ( X , { \ mathbb { R } } ) } denote the set of all functions from Padron : Mvar to real numbers R. Because R is a field , F ( X , R ) { \ displaystyle { \ mathcal { F } } ( X , { \ mathbb { R } } ) } is a vector space and a commutative algebra ( structure ) over reals :.
