Show $p lor (p land q ) equiv p $ using equivalences












0












$begingroup$


I am trying to show $p lor (p land q ) equiv p $ using equivalences.



I have tried many replacements (e.g. distributivity and de Morgans) but cannot see a way to simplify the left hand side that reduces to $p$.



Here are is a list of logical equivalences from wikipedia.



I know that this statement is true (via truth tables), but I cannot derive this using equivalences. Ideas appreciated.










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  • 2




    $begingroup$
    Law of absorption. This is an axiom in lattice theory.
    $endgroup$
    – Wuestenfux
    Dec 14 '18 at 11:39
















0












$begingroup$


I am trying to show $p lor (p land q ) equiv p $ using equivalences.



I have tried many replacements (e.g. distributivity and de Morgans) but cannot see a way to simplify the left hand side that reduces to $p$.



Here are is a list of logical equivalences from wikipedia.



I know that this statement is true (via truth tables), but I cannot derive this using equivalences. Ideas appreciated.










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    Law of absorption. This is an axiom in lattice theory.
    $endgroup$
    – Wuestenfux
    Dec 14 '18 at 11:39














0












0








0





$begingroup$


I am trying to show $p lor (p land q ) equiv p $ using equivalences.



I have tried many replacements (e.g. distributivity and de Morgans) but cannot see a way to simplify the left hand side that reduces to $p$.



Here are is a list of logical equivalences from wikipedia.



I know that this statement is true (via truth tables), but I cannot derive this using equivalences. Ideas appreciated.










share|cite|improve this question











$endgroup$




I am trying to show $p lor (p land q ) equiv p $ using equivalences.



I have tried many replacements (e.g. distributivity and de Morgans) but cannot see a way to simplify the left hand side that reduces to $p$.



Here are is a list of logical equivalences from wikipedia.



I know that this statement is true (via truth tables), but I cannot derive this using equivalences. Ideas appreciated.







logic propositional-calculus boolean-algebra






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share|cite|improve this question













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share|cite|improve this question








edited Dec 14 '18 at 13:36









Bram28

60.5k44590




60.5k44590










asked Dec 14 '18 at 11:35









Conor CosnettConor Cosnett

2241210




2241210








  • 2




    $begingroup$
    Law of absorption. This is an axiom in lattice theory.
    $endgroup$
    – Wuestenfux
    Dec 14 '18 at 11:39














  • 2




    $begingroup$
    Law of absorption. This is an axiom in lattice theory.
    $endgroup$
    – Wuestenfux
    Dec 14 '18 at 11:39








2




2




$begingroup$
Law of absorption. This is an axiom in lattice theory.
$endgroup$
– Wuestenfux
Dec 14 '18 at 11:39




$begingroup$
Law of absorption. This is an axiom in lattice theory.
$endgroup$
– Wuestenfux
Dec 14 '18 at 11:39










2 Answers
2






active

oldest

votes


















3












$begingroup$

This is listed, verbatim, as one of the absorbtion laws in the wikipedia page you linked.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    It's in the list ... but some texts like to derive it as follows:



    $$p lor (p land q) equiv (p land top) lor (p land q) equiv p land (top lor q) equiv p land top equiv p$$






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
      $endgroup$
      – Bram28
      Dec 15 '18 at 21:00










    • $begingroup$
      @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
      $endgroup$
      – Bram28
      Dec 15 '18 at 21:53










    • $begingroup$
      @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
      $endgroup$
      – Bram28
      Dec 16 '18 at 0:10










    • $begingroup$
      RIght - my brain was not in gear!
      $endgroup$
      – Rob Arthan
      Dec 16 '18 at 12:11










    • $begingroup$
      @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
      $endgroup$
      – Bram28
      Dec 16 '18 at 12:33











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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    This is listed, verbatim, as one of the absorbtion laws in the wikipedia page you linked.






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      This is listed, verbatim, as one of the absorbtion laws in the wikipedia page you linked.






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        This is listed, verbatim, as one of the absorbtion laws in the wikipedia page you linked.






        share|cite|improve this answer









        $endgroup$



        This is listed, verbatim, as one of the absorbtion laws in the wikipedia page you linked.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 14 '18 at 11:41









        ArthurArthur

        112k7107191




        112k7107191























            0












            $begingroup$

            It's in the list ... but some texts like to derive it as follows:



            $$p lor (p land q) equiv (p land top) lor (p land q) equiv p land (top lor q) equiv p land top equiv p$$






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:00










            • $begingroup$
              @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:53










            • $begingroup$
              @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
              $endgroup$
              – Bram28
              Dec 16 '18 at 0:10










            • $begingroup$
              RIght - my brain was not in gear!
              $endgroup$
              – Rob Arthan
              Dec 16 '18 at 12:11










            • $begingroup$
              @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
              $endgroup$
              – Bram28
              Dec 16 '18 at 12:33
















            0












            $begingroup$

            It's in the list ... but some texts like to derive it as follows:



            $$p lor (p land q) equiv (p land top) lor (p land q) equiv p land (top lor q) equiv p land top equiv p$$






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:00










            • $begingroup$
              @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:53










            • $begingroup$
              @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
              $endgroup$
              – Bram28
              Dec 16 '18 at 0:10










            • $begingroup$
              RIght - my brain was not in gear!
              $endgroup$
              – Rob Arthan
              Dec 16 '18 at 12:11










            • $begingroup$
              @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
              $endgroup$
              – Bram28
              Dec 16 '18 at 12:33














            0












            0








            0





            $begingroup$

            It's in the list ... but some texts like to derive it as follows:



            $$p lor (p land q) equiv (p land top) lor (p land q) equiv p land (top lor q) equiv p land top equiv p$$






            share|cite|improve this answer









            $endgroup$



            It's in the list ... but some texts like to derive it as follows:



            $$p lor (p land q) equiv (p land top) lor (p land q) equiv p land (top lor q) equiv p land top equiv p$$







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Dec 14 '18 at 12:49









            Bram28Bram28

            60.5k44590




            60.5k44590












            • $begingroup$
              @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:00










            • $begingroup$
              @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:53










            • $begingroup$
              @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
              $endgroup$
              – Bram28
              Dec 16 '18 at 0:10










            • $begingroup$
              RIght - my brain was not in gear!
              $endgroup$
              – Rob Arthan
              Dec 16 '18 at 12:11










            • $begingroup$
              @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
              $endgroup$
              – Bram28
              Dec 16 '18 at 12:33


















            • $begingroup$
              @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:00










            • $begingroup$
              @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
              $endgroup$
              – Bram28
              Dec 15 '18 at 21:53










            • $begingroup$
              @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
              $endgroup$
              – Bram28
              Dec 16 '18 at 0:10










            • $begingroup$
              RIght - my brain was not in gear!
              $endgroup$
              – Rob Arthan
              Dec 16 '18 at 12:11










            • $begingroup$
              @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
              $endgroup$
              – Bram28
              Dec 16 '18 at 12:33
















            $begingroup$
            @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
            $endgroup$
            – Bram28
            Dec 15 '18 at 21:00




            $begingroup$
            @RobArthan That's an instance of Distribution ... which is often not derived from other equivalence principles. That is, Distribution is often a given equivalence principle.
            $endgroup$
            – Bram28
            Dec 15 '18 at 21:00












            $begingroup$
            @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
            $endgroup$
            – Bram28
            Dec 15 '18 at 21:53




            $begingroup$
            @RobArthan By Distribution I mean $p land (q lor r) equiv (p land q) lor (p land r)$
            $endgroup$
            – Bram28
            Dec 15 '18 at 21:53












            $begingroup$
            @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
            $endgroup$
            – Bram28
            Dec 16 '18 at 0:10




            $begingroup$
            @RobArthan Why not? $p=p$, $q= top$, and $r=q$ ...
            $endgroup$
            – Bram28
            Dec 16 '18 at 0:10












            $begingroup$
            RIght - my brain was not in gear!
            $endgroup$
            – Rob Arthan
            Dec 16 '18 at 12:11




            $begingroup$
            RIght - my brain was not in gear!
            $endgroup$
            – Rob Arthan
            Dec 16 '18 at 12:11












            $begingroup$
            @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
            $endgroup$
            – Bram28
            Dec 16 '18 at 12:33




            $begingroup$
            @RobArthan No worries! It was probably because it went in the 'opposite' direction of what you normally understand 'Distribution' to be ... more like a 'Reverse Distribution' or 'Un-Distribution' or 'Factoring'
            $endgroup$
            – Bram28
            Dec 16 '18 at 12:33


















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