How to Interpret the Basic Logic Problem with Predicate P(x,y,z)

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The discussion focuses on interpreting a logic problem involving the predicate P(x,y,z) and how the variable z is utilized. The main challenge is understanding how to demonstrate that the statement "False" can be derived from the given logical expression. Participants clarify that the expression can be true if either predicate is false, and they explore the relationships between x, y, and z using a truth table. The confusion arises from the application of z, as it is not clearly defined in the context of the problem. Overall, the conversation emphasizes the complexities of logical interpretation and the importance of understanding variable relationships in predicate logic.
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Homework Statement


I refer to part G of this little problem:

Screen Shot 2018-09-10 at 11.50.48 PM.png


I don't see how to arrive at any conclusion, especially when I can't even see how ##z## comes into play. Assistance in interpreting the problem is appreciated!

Homework Equations

The Attempt at a Solution



I know that the answer for G is "False", which means I have to show that the following is true;
$$\exists x \in A, \ \forall y \in A, \exists z \in A, \ \neg P(x,y) \lor \neg P(y,z)$$

Here's how I have tried to interpret the problem.
$$\neg P(x,y) \lor \neg P(y,z)$$
is true when either or both predicates are false. Looking at a particular ##x## and all combinations of ##y## that come with it (##\exists x \in A, \ \forall y \in A##), none of them are able to make ##P(x,y)## false all the time.

So now I try to look at all ##y## (that are already paired with some ##x##) and try to find some ##z## for each of the ##y## that would cause ##p(z,y)## to always be false. However, I'm not sure where and how to apply the ##z## since it's not defined in the table.

Was this how I am supposed to interpret the problem? Apologies if what I have written is unintelligible as I am finding logic rather confusing.
 

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the table of truth of P(y,z) is the same as table of truth for P(x,y) with two differences: where x you put y and where y you put z.
that is it is
y 0 1 2
z \
0 T F T
1 T T F
2 T F F​

I see the table I tried to make using standard text editing doesn't look that good but I think you ll understand it. for example it is P(y,z)=T for y=0 and z=0, P(y,z)=F for y=1 and z=0, P(y,z)=T for y=2 and z=0...
 
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WWCY said:

Homework Statement


I refer to part G of this little problem:

View attachment 230498

I don't see how to arrive at any conclusion, especially when I can't even see how ##z## comes into play. Assistance in interpreting the problem is appreciated!

Homework Equations



The Attempt at a Solution



I know that the answer for G is "False", which means I have to show that the following is true;
##\ \exists x \in A, \ \forall y \in A, \exists z \in A, \ \neg P(x,y) \lor \neg P(y,z)##

Here's how I have tried to interpret the problem.
##\ \neg P(x,y) \lor \neg P(y,z)##
...
Don't be fixated on what variable name is used for a particular index (parameter) .

For example: If we set x = 0 and y = 1, then P(x,y) is True. However P(y,x) is False for the same choices of x and y, because this is P(1,0) .
 
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Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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