Variations on implication
Lulu of the Lotus-Eaters
mertz at gnosis.cx
Wed Feb 12 19:17:49 CET 2003
|> Paul Rubin wrote:
|> > => is the traditional mathematical symbol for boolean implication.
|> > -> looks more to me like some kind of pointer operation. But either
|> > one is ok with me for this.
Michael Hudson <mwh at python.net> wrote previously:
|In which context? In my world, => is implication. It's even
|$\implies$ in LaTeX, I think. -> is often used to denote a map.
FWIW, my math background is primarily in logic, model theory, and set
theory. In those contexts, there is often a convention of using the
single line "->" for syntactic implication, i.e. predicate logic. The
double line "=>" is reserved for semantic implication. So you might
write (in a simple case):
A -> B
B -> C
=>
A -> C
Or: given the predicates "A implies B" and "B implies C", you are
authorized to derive the predicate "A implies C" (syllogism).
Yours, Lulu...
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