How to tell if this propositional logic statement is valid?











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$$W ∧ X ∧ Y ⊨ Z text{ if and only if } ⊨ W → (X → (Y → Z))$$




I know it can be done using truth tables but I'm stuck on the "if and only if ⊨", I don't understand what that means.










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    up vote
    0
    down vote

    favorite













    $$W ∧ X ∧ Y ⊨ Z text{ if and only if } ⊨ W → (X → (Y → Z))$$




    I know it can be done using truth tables but I'm stuck on the "if and only if ⊨", I don't understand what that means.










    share|cite|improve this question


























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite












      $$W ∧ X ∧ Y ⊨ Z text{ if and only if } ⊨ W → (X → (Y → Z))$$




      I know it can be done using truth tables but I'm stuck on the "if and only if ⊨", I don't understand what that means.










      share|cite|improve this question
















      $$W ∧ X ∧ Y ⊨ Z text{ if and only if } ⊨ W → (X → (Y → Z))$$




      I know it can be done using truth tables but I'm stuck on the "if and only if ⊨", I don't understand what that means.







      logic propositional-calculus






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      edited Nov 23 at 15:23









      Mauro ALLEGRANZA

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      63.6k448110










      asked Nov 23 at 14:58









      esperski

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          'A if and only if B' is written symbolically as $ A iff B$ and it means that whenever A happens B happens too and whenever $B$ happens $A$ happens too. It is just math talk for: "these things imply one another." Your truth table calculations should reveal that these two things always imply one another.






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            1 Answer
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            up vote
            0
            down vote













            'A if and only if B' is written symbolically as $ A iff B$ and it means that whenever A happens B happens too and whenever $B$ happens $A$ happens too. It is just math talk for: "these things imply one another." Your truth table calculations should reveal that these two things always imply one another.






            share|cite|improve this answer

























              up vote
              0
              down vote













              'A if and only if B' is written symbolically as $ A iff B$ and it means that whenever A happens B happens too and whenever $B$ happens $A$ happens too. It is just math talk for: "these things imply one another." Your truth table calculations should reveal that these two things always imply one another.






              share|cite|improve this answer























                up vote
                0
                down vote










                up vote
                0
                down vote









                'A if and only if B' is written symbolically as $ A iff B$ and it means that whenever A happens B happens too and whenever $B$ happens $A$ happens too. It is just math talk for: "these things imply one another." Your truth table calculations should reveal that these two things always imply one another.






                share|cite|improve this answer












                'A if and only if B' is written symbolically as $ A iff B$ and it means that whenever A happens B happens too and whenever $B$ happens $A$ happens too. It is just math talk for: "these things imply one another." Your truth table calculations should reveal that these two things always imply one another.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Nov 23 at 15:03









                Mason

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                1,9031426






























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