page097_example2.44_2

hughmcguire

Proof of the following formula: 

//page097_example2.44_2
¬[∃x(r(x) ∧ s(x))]

(#) Comments   Theorem and subgoals
      We start working with the formula being proved
as follows:
(1) page097_example2.44_2   
¬[∃x(r(x) ∧ s(x))]
          ≡      by rewriting the form "¬∃ν[φ]"
                to "∀ν[¬φ]"
(2)     
∀x¬(r(x) ∧ s(x))
          ≡      by rewriting the form "¬(φ1 ∧ φ2)"
                to "(¬φ1 ∨ ¬φ2)"
(3)  [unused]   
∀x(¬[r(x)] ∨ ¬[s(x)])

identification:
1234112711454
1234112693034
18420