Logic homework help?

**Poseidon** · February 5th, 2002, 04:14 PM

Does this help:

. . . . In addition, we can use System P to show propositions to be truth-functional tautologies, contradictions or contingencies; to be truth-functionally consistent or inconsistent; and to be truth functionally equivalent or non-equivalent.. . . ? here

The above is from a cached google page

grrrrrr having trouble getting the URL to post correctely

<a href="http://www.google.com/search?q=cache:dVSvLJahkaMC:www.philosophy.ubc.ca/faculty/fleming/ch6.htm+functionally+consistent&hl=en" target="_blank">here</a>

**Renée** · February 5th, 2002, 10:13 PM

[quote]Originally posted by Sowulo:


I used to teach at a local University....A good instructor will see be able to recognize a problem when most everyone misses the same question/problem and remove it from grading consideration. Then, if it's a real important point, readdress the information and include it in the next test....<hr></blockquote>

Well, I sure hope my professor is just like you!!

**WebHead** · February 5th, 2002, 10:56 PM

OK,.. I was doing a little searching on the internet. And since I don't have a clue as to what the hell I'm talking about, you could just disregard this if it doesn't help.

First of all, I found functional consistency, and I found truth-functional consistency. But I could never find both on the same page. You're trying to find out the difference between the 2 right?

Here's the definition of truth-functional consistency from what I found:
a wff is TF consistent iff the column in a full truth table under its principal symbol contains at least one T. (Not every statement symbolized by a TF consistent wff is consistent. Consider "Not all plants are plants." What is the relation between TF consistency and TF contradiction?)

And I couldn't find the definition of function consistency. I found the word used here and there, but no real definitions in order to distinquish the 2. Could it be possible that truth-function is a more formal term used in place of just function? Do you find both terms in the books index? Have you gone to the library in the school, and referenced other programming logic books to see what they have?

**Renée** · February 6th, 2002, 08:59 PM

[quote]Originally posted by WebHead:
OK,.. I was doing a little searching on the internet. And since I don't have a clue as to what the hell I'm talking about, you could just disregard this if it doesn't help.

First of all, I found functional consistency, and I found truth-functional consistency. But I could never find both on the same page. You're trying to find out the difference between the 2 right?<hr></blockquote>

Yes, exactly. And I'm just extremely pleased that you tried to help me, Webby!

[quote]Here's the definition of truth-functional consistency from what I found:
a wff is TF consistent iff the column in a full truth table under its principal symbol contains at least one T. (Not every statement symbolized by a TF consistent wff is consistent. Consider "Not all plants are plants." What is the relation between TF consistency and TF contradiction?)<hr></blockquote>

Yep, that's it precisely. "wff" stands for well-formed formula. "iff" stands for if and only if.

[quote]And I couldn't find the definition of function consistency. I found the word used here and there, but no real definitions in order to distinquish the 2. Could it be possible that truth-function is a more formal term used in place of just function?<hr></blockquote>

You're thinking exactly what the rest of us in the class were thinking. Only when we asked the teacher, he said there is a specific difference. We were all confused.

[quote] Do you find both terms in the books index? Have you gone to the library in the school, and referenced other programming logic books to see what they have?<hr></blockquote>

No, couldn't find it in the book anywhere...and, get this...the teacher wrote the book. The book is actually still in draft form, as in it hasn't been published yet (we're his textbook guinea pigs so to speak), so there is no index to look it up in. And by the time I finished this hellacious test, it would have been too late for me to make it to the library and have any time to look it up there.

Again, I really appreciate all the help. The test was turned in on Monday, and we won't get grades back until Thursday night. Or at least I hope he has them graded by then. Since everybody was nice enough to try and help poor ol' me, I'll be nice enough to let you know what the deal was when I get my paper back!