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Symbolising "Only If"

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Estaran
 
Reply Sun 22 Mar, 2009 01:30 am
Hi everyone, just wondering if someone could help me out: How would one symbolise "only if" into PL? Not "if and only if", just "only if".
For example:
I will stay home only if it is raining.

Should this be symbolised with a bi-conditional?
Or H -> R?

I guess it really depends how you interpret the English based on context, but I was wondering if there's some kind of convention for which to use.
 
Phronimos
 
Reply Sun 22 Mar, 2009 01:43 am
@Estaran,
I believe only if is used to introduce the consequent of a conditional, at least thats the general rule that works most of the time. Notations vary, but the one I'm familiar with is the ---> (the backwards C is the other one I think).

So for your example it would be H -> R.
 
kennethamy
 
Reply Mon 30 Mar, 2009 06:50 am
@Estaran,
Estaran wrote:
Hi everyone, just wondering if someone could help me out: How would one symbolise "only if" into PL? Not "if and only if", just "only if".
For example:
I will stay home only if it is raining.

Should this be symbolised with a bi-conditional?
Or H -> R?

I guess it really depends how you interpret the English based on context, but I was wondering if there's some kind of convention for which to use.



H > R

"If" always signals the antecedent.
"only if" always signals the consequent.
 
 

 
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