Return-Path: Delivery-Date: Received: from ted.cs.uidaho.edu by swan.cl.cam.ac.uk with SMTP (PP-6.0) id <03396-0@swan.cl.cam.ac.uk>; Wed, 15 Jul 1992 09:23:44 +0100 Received: by ted.cs.uidaho.edu (16.6/1.34) id AA10327; Wed, 15 Jul 92 01:14:03 -0700 Sender: info-hol-request@edu.uidaho.cs.ted Errors-To: info-hol-request@edu.uidaho.cs.ted Received: from Maui.CS.UCLA.EDU by ted.cs.uidaho.edu (16.6/1.34) id AA10322; Wed, 15 Jul 92 01:13:58 -0700 Received: from LocalHost.cs.ucla.edu by maui.cs.ucla.edu (Sendmail 5.61c+YP/3.19) id AA01480; Wed, 15 Jul 92 01:15:03 -0700 Message-Id: <9207150815.AA01480@maui.cs.ucla.edu> To: info-hol@edu.uidaho.cs.ted Cc: chou@edu.ucla.cs Subject: Recursive definition over sets Date: Wed, 15 Jul 92 01:15:00 PDT From: chou@edu.ucla.cs (I apologize for the previous empty message; I hit the wrong key.) Let f : * -> num be a mapping from "indices" to numbers and s : * -> bool be a set of indices. One can consider the summation, SUM f s, of f(x)'s with x ranging over s, such that SUM f {} = 0 SUM f (x INSERT s) = (x IN s) => (SUM f s) | (f x + SUM f s) Similarly, one can consider maximum, minimum, product, etc. over sets; in fact, for any operation that is independent of the order in which the operation is done. My question is: Has anyone written the necessary code for performing this kind of "recursive definitions" over sets? I'd appreciate anything that can save me the trouble of hacking it myself. - Ching Tsun