MHB How to Approach a Logic Proof Involving Conditionals?

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The discussion focuses on how to approach a logic proof involving conditionals, specifically using the given premises: ~P implies U, P implies F, and F implies U, to prove U. Participants suggest clarifying the context and notation used in the proof, emphasizing the importance of proper formatting in LaTeX for logical expressions. The original poster expresses difficulty in starting proofs and seeks guidance on applying the 19 rules of inference. A suggestion is made to assume the negation of U for a proof by contradiction. The conversation highlights the need for clear communication of concepts and rules in formal logic proofs.
averyjedwards2
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hi! I've been studying formal proofs for my logic final and i had a question on this one that i found in my textbook:
1.)~P\supset(horseshoe)U
2.)P\supsetF
3.)F\supsetU\thereforeU

i just have had a little trouble in the past getting started with proofs. Can anyone give me a little push and maybe start me out with this proof? thank you!
 
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Re: Formal Proofs Help!

Hi!

First, since you are already using LaTeX commands, I suggest enclosing your formulas in dollar signs. Note, however, that tokens that start with a letter must be separated from a previous command (that start with a backslash) with a space. For example, F should be separates from the preceding \supset, which gives $\supset F$. Otherwise, \supsetF will be considered as one undefined command.

Second, I am not sure what your problems are about: sets, propositional logic or something else. Please describe the context and the notations used, such as ~, $U$ and $F$.
 
Re: Formal Proofs Help!

okay thanks for the help! also I'm working on proving this using the 19 rules of inference
 
Re: Formal Proofs Help!

averyjedwards2 said:
I'm working on proving this using the 19 rules of inference
This helps, but you have not answered other questions.
 
Re: Formal Proofs Help!

averyjedwards2 said:
hi! I've been studying formal proofs for my logic final and i had a question on this one that i found in my textbook:
1.)~P\supset(horseshoe)U
2.)P\supsetF
3.)F\supsetU\thereforeU

i just have had a little trouble in the past getting started with proofs. Can anyone give me a little push and maybe start me out with this proof? thank you!

You mean Given :

1. ~P=>U

2. P=>F

3. F=>U ,then prove U

4. ~U..............ASSUMPTION for contradiction
 
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