Show (p ∧ q) → q ≡ T by using table 6 and the first line of table 7












2












$begingroup$


I used the left side to attempt to prove it was T.
Chart of Laws



(p ∧ q) → q ≡ T



(p ∧ q) → q



Using the first line in table 7



¬(p ∧ q) v q



D'Morgans Law



(¬p v ¬q) v q



Associative Law



¬p v (¬q v q)



Negation Law



¬p v T



Domination Law



T ≡ T



I was wondering if this is right since I felt that you can't do that with domination law. If anyone could double check thank you.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
    $endgroup$
    – Bram28
    Jan 25 at 0:42






  • 1




    $begingroup$
    Only one little error, it's De Morgan, not D'Morgan
    $endgroup$
    – Bernard Massé
    Jan 25 at 0:43
















2












$begingroup$


I used the left side to attempt to prove it was T.
Chart of Laws



(p ∧ q) → q ≡ T



(p ∧ q) → q



Using the first line in table 7



¬(p ∧ q) v q



D'Morgans Law



(¬p v ¬q) v q



Associative Law



¬p v (¬q v q)



Negation Law



¬p v T



Domination Law



T ≡ T



I was wondering if this is right since I felt that you can't do that with domination law. If anyone could double check thank you.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
    $endgroup$
    – Bram28
    Jan 25 at 0:42






  • 1




    $begingroup$
    Only one little error, it's De Morgan, not D'Morgan
    $endgroup$
    – Bernard Massé
    Jan 25 at 0:43














2












2








2





$begingroup$


I used the left side to attempt to prove it was T.
Chart of Laws



(p ∧ q) → q ≡ T



(p ∧ q) → q



Using the first line in table 7



¬(p ∧ q) v q



D'Morgans Law



(¬p v ¬q) v q



Associative Law



¬p v (¬q v q)



Negation Law



¬p v T



Domination Law



T ≡ T



I was wondering if this is right since I felt that you can't do that with domination law. If anyone could double check thank you.










share|cite|improve this question











$endgroup$




I used the left side to attempt to prove it was T.
Chart of Laws



(p ∧ q) → q ≡ T



(p ∧ q) → q



Using the first line in table 7



¬(p ∧ q) v q



D'Morgans Law



(¬p v ¬q) v q



Associative Law



¬p v (¬q v q)



Negation Law



¬p v T



Domination Law



T ≡ T



I was wondering if this is right since I felt that you can't do that with domination law. If anyone could double check thank you.







discrete-mathematics logic






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 25 at 0:26







hentaidaddy666

















asked Jan 25 at 0:17









hentaidaddy666hentaidaddy666

112




112












  • $begingroup$
    Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
    $endgroup$
    – Bram28
    Jan 25 at 0:42






  • 1




    $begingroup$
    Only one little error, it's De Morgan, not D'Morgan
    $endgroup$
    – Bernard Massé
    Jan 25 at 0:43


















  • $begingroup$
    Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
    $endgroup$
    – Bram28
    Jan 25 at 0:42






  • 1




    $begingroup$
    Only one little error, it's De Morgan, not D'Morgan
    $endgroup$
    – Bernard Massé
    Jan 25 at 0:43
















$begingroup$
Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
$endgroup$
– Bram28
Jan 25 at 0:42




$begingroup$
Yes, that's fine ... the $p$'s, $q$'s and $r$'s in these laws can be any statement
$endgroup$
– Bram28
Jan 25 at 0:42




1




1




$begingroup$
Only one little error, it's De Morgan, not D'Morgan
$endgroup$
– Bernard Massé
Jan 25 at 0:43




$begingroup$
Only one little error, it's De Morgan, not D'Morgan
$endgroup$
– Bernard Massé
Jan 25 at 0:43










1 Answer
1






active

oldest

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$begingroup$

Yes that's completely correct.



The domination law states that $q lor T$ is always true for any statement $q$. So it's true especially for any negated statement $neg p equiv q$.



Another way to think about this is to consider:



$$(neg p lor T) equiv negneg (neg p lor T) equiv neg(p land F) equiv neg F equiv T$$



that is using the double negation law and then applying De Morgan's laws one time to use the domination law directly with the $land$ operator.






share|cite|improve this answer











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    $begingroup$

    Yes that's completely correct.



    The domination law states that $q lor T$ is always true for any statement $q$. So it's true especially for any negated statement $neg p equiv q$.



    Another way to think about this is to consider:



    $$(neg p lor T) equiv negneg (neg p lor T) equiv neg(p land F) equiv neg F equiv T$$



    that is using the double negation law and then applying De Morgan's laws one time to use the domination law directly with the $land$ operator.






    share|cite|improve this answer











    $endgroup$


















      0












      $begingroup$

      Yes that's completely correct.



      The domination law states that $q lor T$ is always true for any statement $q$. So it's true especially for any negated statement $neg p equiv q$.



      Another way to think about this is to consider:



      $$(neg p lor T) equiv negneg (neg p lor T) equiv neg(p land F) equiv neg F equiv T$$



      that is using the double negation law and then applying De Morgan's laws one time to use the domination law directly with the $land$ operator.






      share|cite|improve this answer











      $endgroup$
















        0












        0








        0





        $begingroup$

        Yes that's completely correct.



        The domination law states that $q lor T$ is always true for any statement $q$. So it's true especially for any negated statement $neg p equiv q$.



        Another way to think about this is to consider:



        $$(neg p lor T) equiv negneg (neg p lor T) equiv neg(p land F) equiv neg F equiv T$$



        that is using the double negation law and then applying De Morgan's laws one time to use the domination law directly with the $land$ operator.






        share|cite|improve this answer











        $endgroup$



        Yes that's completely correct.



        The domination law states that $q lor T$ is always true for any statement $q$. So it's true especially for any negated statement $neg p equiv q$.



        Another way to think about this is to consider:



        $$(neg p lor T) equiv negneg (neg p lor T) equiv neg(p land F) equiv neg F equiv T$$



        that is using the double negation law and then applying De Morgan's laws one time to use the domination law directly with the $land$ operator.







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited Jan 25 at 3:16

























        answered Jan 25 at 0:24







        user635162





































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