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Homework Help: Truth tables

  1. Jan 20, 2007 #1
    1. The problem statement, all variables and given/known data

    This is just a simple logic question that I need a little guidance.
    Let X= "I like cars"
    Let Y= "I like trees"
    Let ~ = not
    Let V = or

    How would this be written in symbols:
    1. It is not the case that I like cars or I like trees
    2. It is not the case that I like cars, or I like trees

    2. Relevant equations

    none

    3. The attempt at a solution

    1. ~X V Y
    2. ~(X V Y)
     
  2. jcsd
  3. Jan 21, 2007 #2
    your answers should be vice versa I think
     
  4. Jan 21, 2007 #3

    HallsofIvy

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    First statement: "It is not the case that: (I like cars or I like trees).

    Second statement: (It is not the case that I like cars) or (it is not the case that I like trees).

    I agree with theperthvan.
     
  5. Jan 21, 2007 #4
    that's what I thought, but the examples in the book gives the following:

    P=Irene has red hair

    PV~P = "Irene has red hair or she dos not have red hair"

    if what you say is correct, then the example should say:

    PV~P = "Irene has red hair, or she dos not have red hair"
     
  6. Jan 21, 2007 #5

    HallsofIvy

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    ?? The only difference I see is a comma which, grammatically, is optional here. Both sentences mean the same thing.
     
  7. Jan 21, 2007 #6
    then shouldn't this be the same thing as well?
    1. It is not the case that I like cars or I like trees
    2. It is not the case that I like cars, or I like trees

    Say X- I like cars and Y=I like trees
    then using the example from the book
    i could say ~X V Y, which would read: "I do not like cars or I like trees"

    looking back at
    1. It is not the case that I like cars or I like trees

    would this be ~X V Y and not ~(X V Y)
     
  8. Jan 21, 2007 #7
    The statement: "It is not the case that I like cars, or I like trees" also could read "(It is not the case that I like cars) or (It is the case that I like trees)".
     
    Last edited: Jan 21, 2007
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