logical equality

slovac

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Feb 5, 2015
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Could you please help me?
I have a system which behaves this way:
y = 5 only if x > 1 and x > 1 only if y = 5. So, when I see y = 5, I am sure that x > 1.
Could you please tell me whether the system's behavior can be described as follows?

x > 1 EQ (logical equality) y = 5

Thank you
 
Could you please help me?
I have a system which behaves this way:
y = 5 only if x > 1 and x > 1 only if y = 5. So, when I see y = 5, I am sure that x > 1.
Could you please tell me whether the system's behavior can be described as follows?

x > 1 EQ (logical equality) y = 5

Thank you
First, just a matter of notational shorthand:
y = 5 only if x > 1 and x > 1 only if y = 5
can be written as
y = 5 if and only if x > 1
which can be shortened to
y = 5 iff x > 1

Not quite, but close. The statement
x>1 EQ y=5
is not true in itself because it does not have the iff statement (or equivalent). You would need to add that some sort of way. If that is what you meant by your statement, for example
(y = 5 iff x > 1) -> (x>1 EQ y=5)
where -> means the logical implication, then I would say that is a true statement [or to put it another way, yes the system can be described that way].
 
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