let D be set ; :: thesis: for p, q being Element of D * holds FlattenSeq <*p,q*> = p ^ q
let p, q be Element of D * ; :: thesis: FlattenSeq <*p,q*> = p ^ q
consider g being BinOp of (D *) such that
A1: for d1, d2 being Element of D * holds g . (d1,d2) = d1 ^ d2 and
A2: FlattenSeq <*p,q*> = g "**" <*p,q*> by Def1;
thus FlattenSeq <*p,q*> = g . (p,q) by A2, FINSOP_1:12
.= p ^ q by A1 ; :: thesis: verum