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Esmy

Use truth tables to test the validity of the argument. p → ~q q → ~p ∴ p ∨ q

  • one year ago
  • one year ago

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  1. Esmy
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    this is valid

    • one year ago
  2. Esmy
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    Case p=T and q=T [(p -> ~q) ^ (q -> ~p)] -> (p V q) [(T -> ~T) ^ (T -> ~T)] -> (T V T) [(T -> F ) ^ (T -> F)] -> T [ F ^ F ] -> T F -> T T

    • one year ago
  3. Esmy
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    All four cases come out T, so the argument is valid. I think lol.

    • one year ago
  4. A.Avinash_Goutham
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    u need to verify that using a truth table?

    • one year ago
  5. Esmy
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    p q ~p ~q p -> ~q q -> ~p p v q T T F F F F T T F F T T T T F T T F T T T F F T T T T F Hmmm... I change my answer its invalid

    • one year ago
  6. A.Avinash_Goutham
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    then u need to make a dumbo table with all the combinations of p and q and verify it or u can use this p->q = (~p) v q

    • one year ago
  7. Esmy
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    "p -> ~q" and "q -> ~p" the last row has T and T so the conclusion is false?

    • one year ago
  8. A.Avinash_Goutham
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    actuall it mean that u shud conside the cases on when both of them are true

    • one year ago
  9. Esmy
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    Oh I totally miss understood the question

    • one year ago
  10. Esmy
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    So how would you do that? :o

    • one year ago
  11. Esmy
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    help can you explain to how you do it :/

    • one year ago
  12. A.Avinash_Goutham
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    consider those case when p → ~q q → ~p are true find them

    • one year ago
  13. Esmy
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    can you explain like in steps :/ I understand in steps.

    • one year ago
  14. A.Avinash_Goutham
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    hmm consider those inputs for which p → ~q is true q → ~p is true

    • one year ago
  15. Esmy
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    umhmm :o

    • one year ago
  16. A.Avinash_Goutham
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    lol sorry....... u shud try and understand

    • one year ago
  17. A.Avinash_Goutham
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    ok fine q → ~p is true for first three columns in the table

    • one year ago
  18. Esmy
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    uhmm :o

    • one year ago
  19. Esmy
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    p q ~p ~q ∼p∨q (∼p∨q)→ ∼q ———————————————————————————————— T T F F T F T F F T F T F T T F T F F F T T T T Like this :D

    • one year ago
  20. Esmy
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    Help D:

    • one year ago
  21. A.Avinash_Goutham
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    u dont need help gal jus think

    • one year ago
  22. Esmy
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    Blagh I am thats why I'm asking if I did right or not

    • one year ago
  23. Esmy
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    Okay I'm guessing i didn't do that one right so ill work on another one.

    • one year ago
  24. A.Avinash_Goutham
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    lol draw truth tables for p → ~q q → ~p and pvq see when p → ~q q → ~p are true pvq is true

    • one year ago
  25. Esmy
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    (~p V q) --> ~q (~T V F) --> ~F (F V F) --> T F --> T T So (~p V q) --> ~q is true.

    • one year ago
  26. Esmy
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    there

    • one year ago
  27. Esmy
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    Blagh W/e I'm right I've done everything... :l

    • one year ago
  28. Esmy
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    q p (q → ~p) → (q ∧ ~p) T T T T F T F T F F F F

    • one year ago
  29. satellite73
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    the first two statements are identical \[p\to \lnot q\iff q\to \lnot p\] one is the contrapositive of the other

    • one year ago
  30. Esmy
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    hmmm is my table okay :/ ?

    • one year ago
  31. Esmy
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    I've done like three so far -_-

    • one year ago
  32. satellite73
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    let me right it correctly \[\begin{array}{|c|c|c|c|c|c} P & Q & \lnot{}P & \lnot{}Q & P\to\lnot{}Q & Q\to\lnot{}P \\ \hline T & T & F & F & F & F \\ T& F & F & T & T & T \\ F & T & T & F & T & T \\ F & F & T & T & T & T \\ \hline \end{array}\]

    • one year ago
  33. satellite73
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    write

    • one year ago
  34. phi
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    the final step is put in the column p v q (this is the first problem) An argument is INVALID if and only if it is logically possible for the conclusion to be false even though every premise is assumed to be true.

    • one year ago
  35. satellite73
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    if you want to check your truth table, use this nice site here takes a second to get used to 0 and 1 instead of T and F, and a minute to learn the syntax but it is really useful http://www.kwi.dk/projects/php/truthtable/?

    • one year ago
  36. satellite73
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    but try to think "logically" meaning like a human being instead of using T and F the first statement and the second statement are identical, one is the contrapositive of the other. so you do not need them both, they say the same thing

    • one year ago
  37. Esmy
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    so none of my tables where right :/ ...

    • one year ago
  38. phi
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    this looks ok, The argument is invalid because of the last row p q ~p ~q p -> ~q q -> ~p p v q T T F F F F T T F F T T T T F T T F T T T F F T T T T F Hmmm... I change my answer its invalid

    • one year ago
  39. satellite73
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    P: it is raining Q: i will go to the store \(P\to \lnot Q\) if it is raining then i will not go the the store \(Q\to \lnot P\) if i go to the store, then it is not raining they are identical statements from that, can we conclude that is is raining or i go to the store?

    • one year ago
  40. satellite73
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    of course not! maybe it is sunny and i stay home anyway!

    • one year ago
  41. Esmy
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    Oh okay :o... I c I c

    • one year ago
  42. phi
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    I don't see the other problems..... with premises and conclusion

    • one year ago
  43. Esmy
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    neither do I

    • one year ago
  44. phi
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    I mean, did you post them?

    • one year ago
  45. Esmy
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    yeah I did ?

    • one year ago
  46. phi
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    Is this one of the problems (~p V q) --> ~q ? with premise ~p v q and conclusion ~q

    • one year ago
  47. Esmy
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    I posted my answer and everything D:?

    • one year ago
  48. phi
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    because it looks invalid p q (~p V q) ~q 0 0 1 1 OK 0 1 1 0 INVALID 1 0 0 1 OK 1 1 1 0 INVALID

    • one year ago
  49. Esmy
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    did you do this one or I did I forgot...

    • one year ago
  50. phi
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    somewhere way up above you typed (~p V q) --> ~q (~T V F) --> ~F (F V F) --> T F --> T T So (~p V q) --> ~q is true. I am not sure what the problem is, I'm guessing the first line. But your conclusion is not correct, because you did not test every case

    • one year ago
  51. Esmy
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    Oh lol thats just one of them lol. I did so many that I got lost ... but that I found out wasn't correct after all the thinking ;l

    • one year ago
  52. phi
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    good, sounds like you have a handle on it.

    • one year ago
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