counterexample

mcguireh

Proof of the following formula: 

¬ ∀x [x² = x]

(#)     Theorem and subgoals
      We start working with the formula being proved
as follows:
(1)     
¬ ∀x [x² = x]
      Assigning "x := 2" in that formula yields:
(2)     
¬[2² = 2]
          ≡      by simplifying
(3)     
true
      That concludes the proof.

identification:
1233772874359
1233772864312
10047