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P(x,y,z),   xy=z, Universe is interger;

write in logic form

If xy=x for all y, then x =0.

Thank you
in Mathematical Logic by Junior (851 points) | 81 views

2 Answers

+1 vote
It's a simple "If----then" statement.

Hence, the formulation would be of type $A \rightarrow B$

Here, $A$ is   "xy=x for all y"...Or rephrasing, "For all y, xy = x"

Hence, $A$ = $\forall y (P(x,y,x))$

And $B$ is "$x = 0$"

So, "If xy=x for all y, then x =0" $\equiv$ $\forall y (P(x,y,x))$ $\rightarrow$ ($x = 0$)

You can check the above Propositional expression is Always True.
by Boss (26.4k points)

See this

'=' operator is used here too


'=' operator is used here too

 I have also used...see.. ∀y(P(x,y,x)) → (x=0)

Since, Universe is integer, You could use $x = 0$ if need be.

Sir, what about  ${\forall y (P(x,y,x)) \to P(x,1,0)}$? Can it be a solution?
0 votes
$\forall y\exists x\left (\left (P\left ( x ,y,z\right )=x\right )\rightarrow\left ( xy=x \right )\Lambda \left ( x=0 \right ) \right )$
by Veteran (117k points)
edited by
What "=" stands for ??

And What will be the English interpretation of this expression?
= is just for the interpretation of statement

May be a bracket need to clear the statement "If xy=x for all y, then x =0."


What does it mean? 


ultimately we need to get x as result and we are operating on function P(x,y,z) i.e. P(x,y,z)=x

and for that conditions are (xy=x) and (x=0)

I think it is resolution method

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