reserve p,p1,p2,q,r,F,G,G1,G2,H,H1,H2 for ZF-formula,
  x,x1,x2,y,y1,y2,z,z1,z2,s,t for Variable,
  a,X for set;

theorem Th61:
  Free (p '&' q) = Free p \/ Free q
proof
A1: the_right_argument_of (p '&' q) = q by Th4;
  p '&' q is conjunctive & the_left_argument_of (p '&' q) = p by Th4;
  hence thesis by A1,ZF_MODEL:1;
end;
