Derivations in Predicate Logic

[KCL]

Hi guys,

Im excited about joining this community. I started a thread in the "welcome to new members" section so check it out.

I have three questions I'd like help with. If you could give any general tips for solving these types of problems and help me to solve them that would be great!

1) Derive in PDE the conclusion ~a=b from the premises: (Ax)(x=a › ~Fx) and Fb.
2) Derive in PDE the conclusion (Ex)Rx from the premises: (Ax)(Px › (Ey)(Qxy & Ry)) and (Ax)Px.
3) Derive in PDE the conclusion (Ex)(Ey) ~Gxy from the premises: (Ax)(Ay)(Gxy › Hy) and (Ex) ~Hx.

I've used › as a horseshoe, Ax as the universal quantifier and Ex as the existential qualifier.

Thanks in advance,
Carl

[VideCorSpoon]

PDE in the first year!!! You're almost into metatheorems. Thats like... the end of the universe in PL. Props! Heck, I'm excited for you... thats very advanced. For me, PL took a year after SD (which was a year in itself!!!. Admittedly, my general acquaintance in predicate systems goes up to PD and a little bit of PD+. So I’ll get back to this when I look over the PDE section in my book later today.

Also, did you go through truth trees in predicate logic? For some reason, they always avoided teaching that at school.

[KCL]

Thanks in anticipation...

No we didn't go through truth trees...perhaps they're not viewed as being elegant?

[KCL]

Anyone for some help?
I can swap you for the meaning of life and the Holy Grail..

[Fido]

Originally Posted by KCL

Anyone for some help?
I can swap you for the meaning of life and the Holy Grail..

Some people use words to say and some to play.