How to write statements with negation and disjunction in symbolic form?

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SUMMARY

The discussion focuses on the symbolic representation of negation and disjunction in logic statements. The participants clarify that the first statement, "It is not the case that I like cars or I like trees," is correctly represented as ~(X V Y), while the second statement, "It is not the case that I like cars, or I like trees," can be interpreted as ~(X) V Y. The confusion arises from the grammatical structure, but both interpretations convey the same logical meaning. The participants emphasize the importance of understanding the distinction between negating a disjunction and applying negation to individual statements.

PREREQUISITES
  • Understanding of propositional logic
  • Familiarity with logical operators: negation (~) and disjunction (V)
  • Basic knowledge of symbolic representation in logic
  • Ability to interpret logical statements and their meanings
NEXT STEPS
  • Study the principles of propositional logic and its operators
  • Learn about De Morgan's Laws in logic
  • Explore the differences between conjunction and disjunction in symbolic logic
  • Practice translating complex sentences into symbolic form
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UrbanXrisis
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Homework Statement



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

Homework Equations



none

The Attempt at a Solution



1. ~X V Y
2. ~(X V Y)
 
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your answers should be vice versa I think
 
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.
 
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"
 
?? The only difference I see is a comma which, grammatically, is optional here. Both sentences mean the same thing.
 
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
PV~P = "Irene has red hair or she dos not have red hair"

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

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