reserve x,y,z,x1,x2,y1,y2,z1,z2 for object,
  i,j,k,l,n,m for Nat,
  D for non empty set,
  K for Ring;

theorem Th13:
  for p,q being FinSequence of K holds len (mlt(p,q))=min(len p, len q)
proof
  let p,q be FinSequence of K;
  reconsider r=mlt(p,q) as FinSequence of K;
  r=(the multF of K).:(p,q) by FVSUM_1:def 7;
  hence thesis by FINSEQ_2:71;
end;
