(1) Let V be a real unitary space, A be a subset of V , and x be a set. Then x ∈ Lin(A) if and only if there exists a linear combination l of A such that x = ∑ l. (2) For every real unitary space V and for every subset A of V and for every set x such that x ∈ A holds x ∈ Lin(A). (3) For every real unitary space V holds Lin( / 0the carrier of V ) = 0V . (4) For every real unitary space V and for...