Solution

%% zebra(N) is true if the zebra is the pet of the person with
%% nationality N.
zebra(N) :-
       %% the street is represented as list of 3 houses
       Street = [_House1,_House2,_House3],

       %% a house is represented as a 3-place (color, nationality, pet) complex term
       %% there is a red house in the street
       member(house(red,_,_), Street),

       %% there is a blue house in the street
       member(house(blue,_,_), Street),

       %% there is a green house in the street
       member(house(green,_,_), Street),

       %% the Englishman lives in the red house
       member(house(red,english,_), Street),

       %% the jaguar is the pet of the Spanish family
       member(house(_,spanish,jaguar), Street),

       %% the Japanese lives to the right of the snail keeper
       sublist([house(_,_,snail),house(_,japanese,_)], Street),

       %% the snail keeper lives to the left of the blue house
       sublist([house(blue,_,_),house(_,_,snail)], Street),

       %% the zebra belongs to the person with nationality N
       member(house(_,N,zebra),Street).

%% member and append are built-in predicates, but you have to define
%% sublist and for that you need prefix and suffix. 
prefix(P,L) :- append(P,_,L).

suffix(S,L) :- append(_,S,L).

sublist(SubL,L) :- suffix(S,L),prefix(SubL,S).
    

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