How to Negate Complex Logical Assertions in Mathematics?

  • Thread starter Pythagorean12
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The negation of "p -> q" is NOT "p -> ~q".In summary, the answers to the given assertions are not correct due to the incorrect negation of the "if-then" statements.
  • #1
Pythagorean12
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Homework Statement



Write down the negations of the following assertions (where m, n, a, b are natural numbers):

a) if Coke is not worse than Pepsi then nothing Mandelson says can be trusted.
b) [tex]\forall m \exists n\forall a\forall b (n >= m)[/tex] /\ [tex][(a=1)[/tex] \/[tex] (b=1)[/tex] \/ [tex](ab \ne n)][/tex]

Answers:
a) if Coke is not worse than Pepsi then everything Mandelson says can be trusted.
b) [tex]\exists m\forall n \exists a\exists b (n < m)[/tex] \/[tex][(a \ne 1)[/tex] /\ [tex](b \ne 1)[/tex] /\ [tex](ab =n)][/tex]

Could anyone check whenever or not these answers are correct?
 
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  • #2
Since you have not said what "a", "b", "m", or "n" mean, it is impossible to tell.

I will say this- the negation of an "if- then" implication is NOT an "if-then" implication.
 
  • #3


I cannot provide a definitive answer as to whether these negations are correct or not without more context or information. However, here are some points to consider:

- The negation of "nothing Mandelson says can be trusted" could also be "there is something Mandelson says that can be trusted." Both of these statements are logically equivalent.
- In the second assertion, the negation of "n >= m" would be "n < m", not "n > m". Similarly, the negation of "ab \ne n" would be "ab = n".
- It is unclear what the variables m, n, a, and b represent, so it is difficult to determine if the negations are correct without knowing their specific meanings and relationships.
- It is important to carefully consider the logical structure and implications of the original assertions and their negations to ensure that they accurately reflect the intended meaning.
 

FAQ: How to Negate Complex Logical Assertions in Mathematics?

What is negation in logic?

Negation in logic is the process of expressing the opposite or denial of a statement. It is represented by the symbol "~" or "not". In other words, negation is the act of making a statement false.

How do you negate a logical assertion?

To negate a logical assertion, you must add the word "not" before the statement or use the "~" symbol. For example, if the original statement is "I am tall", the negated statement would be "I am not tall" or "~I am tall".

What is the importance of negating logical assertions?

Negating logical assertions is important because it allows us to consider alternative possibilities and challenge assumptions. It also helps in finding logical inconsistencies and contradictions in arguments.

Can negation change the truth value of a statement?

Yes, negation can change the truth value of a statement. If the original statement is true, then its negation is false, and vice versa. For example, the statement "The sky is blue" is true, but its negation "The sky is not blue" is false.

Are there any rules for negating logical assertions?

There are a few rules for negation in logic, such as De Morgan's laws, which state that the negation of a conjunction is the disjunction of the negations of its components, and the negation of a disjunction is the conjunction of the negations of its components. These rules can be used to simplify complex negations in logic.

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