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%
%  Find the maximum/minimum X of a set of integers S
%  (Declarative solution: an element X of S is the maximum of S, 
%  if for each element Z of S it holds X >= Z)
%
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max(S,X) :-
       X in S &
       forall(Z in S, X >= Z).


% Sample goal:
%
% {log}=> max({3,5,1},X).
%
% X = 5


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min(S,X) :-
       X in S &
       forall(Z in S, X =< Z).


% Sample goal:
%
% {log}=>min({3,5,1},X).
%
% X = 1