🚀 go-pugleaf

In article <rkaivola.718902434@mits> rkaivola@mits.mdata.fi (Risto Kaivola) writes:
>
>  The following is no doubt a little trivial for the participants of this
>group, but I hope someone is willing to help me, nevertheless.
>  Exactly how should one formalize the English notion of 'only if'
>in the language of the propositional calculus?
>  That is, given the sentence
>"Tom will visit us only if we invite him.",
>is the correct formalization
>
>A = "Tom will visit us."
>
>B = "We invite him."
>
>A  -->  B
>
>
>Or, should this perhaps be B --> A (not in my opinion), or A <--> B
>(this last alternative is more likely to be correct than B --> A, in my
>opinion)?
>
>This isn't homework.
>
>--
>Risto Kaivola
>(Internet address:   rkaivola@mits.mdata.fi)

I'd go for:

(B --> A) & (-B --> -A)


Antoni Diller