Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!uwvax!oddjob!uxc!uxc.cso.uiuc.edu!osiris.cso.uiuc.edu!goldfain
From: goldfain@osiris.cso.uiuc.edu
Newsgroups: comp.lang.prolog
Subject: Re: Double Cut - One is enough
Message-ID: <7000004@osiris.cso.uiuc.edu>
Date: 28 Aug 88 21:57:00 GMT
References: <1162@tuhold>
Lines: 23
Nf-ID: #R:tuhold:1162:osiris.cso.uiuc.edu:7000004:000:959
Nf-From: osiris.cso.uiuc.edu!goldfain    Aug 28 16:57:00 1988


> thom@tuhold (Thom Fruehwirth) writes in comp.lang.prolog :
> /* ---------- "Double Cut - One is enough" ---------- */
> The more you program in Prolog, the less cuts you will need.
> Also, at most one cut per clause is enough, as there is a
> simple equivalence preserving program transformation:

> P:- G1,!,G2,!,Gs.  <=>  P:- G1,!,G2Gs.  G2Gs:- G2,!,Gs.

Hmmm.  My personal experience has not been the same.  I think I  use more cuts
than I did years ago.

I also  don't see why the   following has any real relevance   to the  idea of
cut-reduction :

a :- b, !, c, !, d.   <=>   a :- b, !, cd.   cd :- c, !, d.

     It  looks to me as though  you've traded 2 cuts  for   2 cuts -  hardly a
savings.  Sure, you've achieved  a goal of  only one  cut per clause,  but the
code is now worse than it was  before - runs  slower and  as often as not less
understandable than the previous version.

Sorry to be so flamey.                       - Mark Goldfain