Re: Regions

[Greg Lutz <acad!alce!greg>]

Your representation is quite equivalent to the other notation in your
examples ("(-Inf, 0] U [6] U [8, 9) U (9, 20]"), which is more
literally translatable as an array of triples (start, end, eflags),
where eflags is a pair of Booleans telling whether the two brackets are
round or square.  Does your representation have any advantage other
than easy invertibility?  Well, on consideration, maybe another small
one:  a member of the array used in your representation can't be
invalid in itself, whereas in "mine" it could have the "start" and
"end" out of order.  Oh yes: yours also doesn't require any literal
representation for -Inf and +Inf.  I bet that's the big one.