On Fri, 1 Aug 2003, Derek Ross wrote: > Do junctions have a direct representation as predicate logic statements? > In particular, do the following logic statements correspond directly > to the following perl6 junctions: > > LOGIC PERL6 JUNCTION (DESCRIP) > ===== ======================== > (exists x)(x is false) one (abjunction) > > I'm more familiar with), but it seems that the fourth type of junction, > "one" is inconsistent with the logic definition. > > Maybe "one" should be named "one_isnt", or the logic statement should > become (exists a single x)(x is true). Either way, maybe another > junction is needed!
The logic statement should become (exists a unique x) (x is true). This is typically written (exists!)(x is true). No other junction should be necessary: If you want to say that something is *false* for at least one of the values, you can just rephrase that as not (true for all values). On the other hand, if you wanted to say "true for all except exactly one value, I can't think of a way. (but then, nor of a reason for wanting to). > Derek Ross. Abhi.
