Subject: Problems with logic in Sequential ][
Date: Wed, 3 Jun 1998 21:26:59 -0400

My name is Anthony and I take Sequential ][ Math and am taking a practice regents. When doing a logic problem, I encountered the following statements, where I am trying to prove P ( I left out steps unrelated to the question)

~N --> PGiven
~L v ~N(acquired from another part of the proof)
~N ?
This is the part I have trouble with. What law is this? I know this is the right answer, but how do you justify it?

I appreciate your help.

  Hi Anthony

You need to use the definitions of v and of -->.
In particular, A --> B is equivalent to ~A v B.
Thus statement

(3) ~L v ~N

is equivalent to

L --> ~N,

which together with

(1) L

implies (by modus ponens)

(4) ~N.



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