1) I do not have strong opinions for concatenation: either "concat", which is self-explanatory, or "++", which might be a bit more obscure, is good (better than the other alternatives).
2) As for symmetric difference, $\triangle$ is the more standard notation, with a nice ascii version being "/_\". Also, since XOR is in Main, then symmetric difference could be moved to Main too, in my opinion. 3) Regarding logical connectives, I agree with Norm that and/or/implies/iff/not/true/false are sufficient. It is also nice to have XOR, NAND as examples, even though they are not used outside of propcalc. It would be nice to have a subsection with NOR which parallels that for NAND. No need for "negated implies", "(negated) is implied by", and (negated) projections. Benoît -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/metamath/7bf244ec-854e-4ec5-834b-12a219a5c442%40googlegroups.com.
