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Homework Help: Confused on how to do a simple discrete math problem

  1. Feb 21, 2012 #1
    1. The problem statement, all variables and given/known data

    Use the equivalence [itex]p\rightarrow(r \rightarrow s) \equiv p\wedge r\rightarrow s[/itex] to rewrite the following problem before the proof.

    2. Relevant equations

    [itex][p\rightarrow (q\rightarrow r)]\wedge (p\rightarrow q) \tautologicallyimplies (p\rightarrow r)[/itex]


    3. The attempt at a solution

    [itex][p\rightarrow (q\rightarrow r)]\wedge (p\rightarrow q) \tautologicallyimplies (p\rightarrow r)[/itex]

    1. [itex]p\rightarrow (q\rightarrow r) \equiv p\wedge q \rightarrow r \equiv \neg p \vee \neg q \vee r[/itex]
    2. [itex]p\rightarrow q \equiv \neg p \vee q[/itex]

    3. [itex](\neg p \vee q)\wedge (\neg p \vee \neg q \vee r) \equiv ... \equiv p \rightarrow q\wedge r[/itex]

    What am I doing wrong?

    Thanks!
     
  2. jcsd
  3. Feb 21, 2012 #2
    Does anyone know how to do this proof?
     
  4. Feb 21, 2012 #3
    Go back to (p and q) -> r. What does p -> q say about the logical value of (p and q)?
     
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