Logic - 2019-01-21

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New Student

7:33 AM

anyone here ?

most logic books do not answer exercises. is there any book you can propose for self-study

Malice Vidrine

7:53 AM

Bell & Machover's A Course in Mathematical Logic has exercises, but depending on your experience level it may be a little bit rough going.

I forget if Suppes' Intoduction to Logic had exercises; I remember the level of the book being a little friendlier, though, and it's published by Dover so it's cheap.

7 hours later…

user21820

2:53 PM

Q: Semi-recursive ω-rule

I thought of the following semi-recursive ω-rule for a sequence of first-order theories $PA_k$ that extend $PA_0 = PA$: Semi-recursive ω-rule: For each $1$-parameter arithmetical sentence $Q$, if (using the usual encoding) $PA_k \vdash \forall n ( PA_k \vdash Q(n) )$, then we add $∀n ( Q(n) )...

^ It now has a partial answer by Noah.

7 hours later…

user400188

10:23 PM

@MaliceVidrine Suppes' is a good book to learn from, but unfortunately it doesn't use a Fitch style deductive system. This makes it harder for anyone learning from it to ask questions in the room related to it.

Malice Vidrine

10:47 PM

@user400188 Ah, that's fair. I'm afraid I don't have other references offhand. Looking at my bookshelf, I'm realizing that I learned from some rather eccentric sources. :P

user400188

11:30 PM

Does anyone in this room know how to use the proofmood, Fitch style theorem prover?
http://www.proofmood.com/en/Fitch/fitch.php
I've tried to use it on several occasions, but for whatever reason it can't verify any steps I make, even when the proof follows and example one they provide.