mekso binary operator: generate span; outputs span(X1, X= spanX; set of all (finite) sums of terms of form c v, where v is an element of algebraic structure X1 (wherein scalar multiplication and summation is defined), and c is a scalar belonging to ring X2.
For example, the span of vectors v1 and v2 in vector space V over the field of exactly all real numbers R has X1 = Intersect(V, Set(v1, v and X2 = R and yields output Set(c1 v in R for alli), where scalar multiplication and vector addition are as defined in V.