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From: mozetic@uiucdcsb.CS.UIUC.EDU
Newsgroups: net.ai
Subject: Re: HELP!!!!!
Message-ID: <5500034@uiucdcsb>
Date: Fri, 16-May-86 15:48:00 EDT
Article-I.D.: uiucdcsb.5500034
Posted: Fri May 16 15:48:00 1986
Date-Received: Sun, 18-May-86 15:31:18 EDT
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Nf-From: uiucdcsb.CS.UIUC.EDU!mozetic    May 16 14:48:00 1986


% How about the following:

len( 0, [] ).
len( N, [_ | L] ) :- len( N0, L ), N is N0 + 1.

nth( X, 1, [X | _] ).
nth( X, N, [_ | L] ) :- N > 1, N0 is N - 1, nth( X, N0, L ).