reserve x for set,
  D for non empty set,
  k,n,m,i,j,l for Nat,
  K for Field;

theorem Th35:
  for a1,a2,a3,b1,b2,b3,c1,c2,c3 being Element of D holds 
  <*<*a1,a2,a3*>,<*b1,b2,b3*>,<*c1,c2,c3*>*> is Matrix of 3,D
proof
  let a1,a2,a3,b1,b2,b3,c1,c2,c3 be Element of D;
A1: len <*c1,c2,c3*>=3 by FINSEQ_1:45;
  len <*a1,a2,a3*>=3 & len <*b1,b2,b3*>=3 by FINSEQ_1:45;
  hence thesis by A1,Th34;
end;
