To do a tableau proof of this statement:(adsbygoogle = window.adsbygoogle || []).push({});

[tex](\forall x) [P(x) \vee Q(x)] \supset [(\exists x)(P(x) \vee (\exists x)(Q(x)] [/tex]

I started out by restating it as follows:

[tex](\forall x) [P(x) \vee Q(x)] \supset [(\exists y)(P(y) \vee (\exists z)(Q(z)] [/tex]

to avoid confusion over what's bound to what (and when).

Is my approach:

valid?

invalid?

recommended?

not?

a good idea?

not?

some other adjective (or expletive)?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# First order proof

Loading...

**Physics Forums | Science Articles, Homework Help, Discussion**