theorem
  a [*] "\/"(X,Q) = "\/"({a [*] b: b in X}, Q) & a delta "/\"(X,Q) =
  "/\"({a delta c: c in X}, Q)
proof
  deffunc F(Element of Q) = Bottom a [*] $1;
  deffunc G(Element of Q) = Bottom $1;
  deffunc H(Element of Q) = Bottom a [*] Bottom $1;
  defpred P[set] means $1 in X;
  deffunc F1(Element of Q) = Bottom (Bottom a [*] Bottom $1);
  deffunc F2(Element of Q) = a delta $1;
  thus a [*] "\/"(X,Q) = "\/"({a [*] b: b in X}, Q) by Def5;
A1: {F(c): c in {G(d): P[d]}} = {F(G(b)): P[b]} from DenestFraenkel;
A2: {G(c): c in {H(d): P[d]}} = {G(H(b)): P[b]} from DenestFraenkel;
A3: F1(b) = F2(b);
A4: {F1(b): P[b]} = {F2(c): P[c]} from FRAENKEL:sch 5(A3);
  thus a delta "/\"(X,Q) = Bottom (Bottom a [*] "\/"({Bottom b: b in X}, Q))
  by Th25
    .= Bottom "\/"({Bottom a [*] Bottom b: b in X}, Q) by A1,Def5
    .= "/\"({a delta b: b in X}, Q) by A2,A4,Th24;
end;
