Tricky Version

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% Tricky Version 

 :- dynamic acr/3.

try_asserta(F) :- 

 F,
 !.

try_asserta(F) :- 

 !,
 asserta(F).

ackermann(M, N, A) :- 

 acr(M, N, A),
 !.

ackermann(0, N, A) :- 

 !,
 A is N + 1,
 try_asserta(acr(0, N, A)).

ackermann(M, 0, A) :- 

 %M > 0,
 !,
 M1 is M - 1,
 ackermann(M1, 1, A),
 try_asserta(acr(M, 0, A)),
 try_asserta(acr(M1, 1, A)).

ackermann(M, N, A) :- 

 %M > 0,
 %N > 0,
 !,
 M1 is M - 1,
 N1 is N - 1,
 ackermann(M, N1, Temp),
 try_asserta(acr(M, N1, Temp)),
 ackermann(M1, Temp, A),
 try_asserta(acr(M, N, A)),
 try_asserta(acr(M1, Temp, A)).
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