🚀 go-pugleaf

gandalf@Csli.Stanford.EDU (Juergen Wagner) writes:
: [titan.rice.edu seems to have vanished from my name server tables]
: 
: What about setminus with a singleton? I don't see why we need a new
: operator here. I haven't seen any in the literature, either.
: 
: --Juergen Wagner
: J_Wagner@iao.fhg.de
: gandalf@csli.stanford.edu

OK... I quite like the idea so:


== [X] ==================================
| _ sminus _ : |P X x X -> |P X
+----------------------------------------
|forall S:|P X;t:X .
|  S sminus t = { x:X|x in S and x neq t}

where sminus is typeset as, say, \heartsuit.

There you go. Now \heartsuit is your set-minus operator.
Happy?

-- Daniel