Ok, here is a revenge paradox that doesn't mention Uy:
R'' : This sentences is true iff (if it is true then it is false).
(Ty ↔ (Ty → Fy))
This works:
∀x(Fx ∨ (Tx ∨ Ux)), ∀x¬(Fx ∧ Tx),
∀x¬(Fx ∧ Ux), ∀x¬(Tx ∧ Ux) entails ¬(Ty ↔ (Ty → Fy)).
https://www.umsu.de/trees/#~6x(Fx~2Tx~2Ux),~6x(~3(Fx~1Tx)),~6x(~3(Fx~1Ux)),~6x(~3(Tx~1Ux))|=~3(Ty~4(Ty~5Fy))
I got some help from Prolog. And found it with this query:
?- formula(3, X, Y), antinomy(X, (forall(X=t,Y),forall(Y,X=t))).
Y = (X = f; X = u);
Y = (X = u; X = f);
Y = forall(X = t, X = f);
Y = forall(X = t, X = u);
fail.
Prolog source code here:
formula(1, X, X = C) :- !,
value(_, C).
formula(N, X, Y) :- !,
M is N-1, formula(_, M, X, Y).
formula(0, N, X, (\+ Y)) :- formula(N, X, Y).
formula(1, N, X, (Y ; Z)) :- M is N-1, between(1, M, K), J is N-K,
formula(K, X, Y), formula(J, X, Z).
formula(2, N, X, (Y , Z)) :- M is N-1, between(1, M, K), J is N-K,
formula(K, X, Y), formula(J, X, Z).
formula(2, N, X, forall(Y , Z)) :- M is N-1, between(1, M, K), J is N-K,
formula(K, X, Y), formula(J, X, Z).
antinomy(X, Y) :- \+ (value(_, X), Y).
value(0, f).
value(1, u).
value(2, t).