Logic Programming Prolog 3
اسلاید 1: 1member(X,[Y| _ ] ) :- X = Y.member(X, [ _ | Y]) :- member(X, Y).It would be easier to write this as:member(X,[X| _ ]).member(X, [ _ | Y]) :- member(X, Y).?- member(1, [3,4,5,8,1,9]).Yes?- member(X, [prolog, c, ada, haskell]).X= prolog;X= cX= ada;X= haskell;NoRecursion and Lists
اسلاید 2: 2Other Exampleschange(you, i).change(are, [am, not]).change(french, australian).change(do, no).change(X, X). /* catchall */alter([ ], [ ]).alter([H|T], [X|Y]) :- change(H, X), alter(T,Y).?- alter([you,are,a,computer],R).R = [i, [am, not], a, computer] Yes?- alter([you,are,french],R).R = [i, [am, not], australian] Yes?-
اسلاید 3: 3asserta/1.assertz/1assert/1retract/1retractall/1Example:assertz(fib(N,F)).
اسلاید 4: 4:-dynamic fibfib(1,1).fib(2,1).fib(N,F) :-N > 2,N1 is N-1, fib(N1,F1),N2 is N-2, fib(N2,F2),F is F1 + F2,asserta(fib(N,F)).?- fib(8, F).F = 21 ?- fib(6,F).F = 8
اسلاید 5: 5F(6)+f(5)f(4)+f(3) f(2)f(2) f(1)+1 1+f(4) f(3)+f(3) f(2)1 +f(2) f(1)+f(2) f(1)1 1 1 1 1
اسلاید 6: 6asserta/1.assertz/1assert/1retract/1retractall/1Example:assertz(fib(N,F)).
اسلاید 7: 7:-dynamic animal/1. % A directive.animal(tiger).animal(lion).animal(monkey).animal(X):-mamal(X), asserta(animal(X)).mamal(cat).mamal(dog).?- animal(dog).Yes?- listing(animal).:- dynamic animal/1.animal(dog).animal(tiger).animal(lion).animal(monkey).animal(A) :- mamal(A), asserta(animal(A)).
اسلاید 8: 8leng([ ], 0).leng([H|T], Len) :- leng(T, Len1), Len is Len1 + 1.Finding the length of a list
اسلاید 9: 9[trace] ?- leng([1,2,3,4,5],Ln). Call: (6) leng([1, 2, 3, 4, 5], _G405)?creep Call: (7) leng([2, 3, 4, 5], _G474) ? creep Call: (8) leng([3, 4, 5], _G474) ? creep Call: (9) leng([4, 5], _G474) ? creep Call: (10) leng([5], _G474) ? creep Call: (11) leng([], _G474) ? creep Exit: (11) leng([], 0) ? creep^ Call: (11) _G479 is 0+1 ? creep^ Exit: (11) 1 is 0+1 ? creep Exit: (10) leng([5], 1) ? creep^ Call: (10) _G482 is 1+1 ? creep^ Exit: (10) 2 is 1+1 ? creep Exit: (9) leng([4, 5], 2) ? creep^ Call: (9) _G485 is 2+1 ? creep^ Exit: (9) 3 is 2+1 ? creep Exit: (8) leng([3, 4, 5], 3) ? creep^ Call: (8) _G488 is 3+1 ? creep^ Exit: (8) 4 is 3+1 ? creep Exit: (7) leng([2, 3, 4, 5], 4) ? creep^ Call: (7) _G405 is 4+1 ? creep^ Exit: (7) 5 is 4+1 ? creep Exit: (6) leng([1, 2, 3, 4, 5], 5) ? creepLn = 5 Yesleng([ ], 0).leng([H|T], Len) :- leng(T, Len1), Len is Len1 + 1.
اسلاید 10: 10remove(X, [ ], [ ]).remove(X, [X|T], C):-remove(X,T,C).remove(X, [H|T], [H|T1]):- X = H,remove(X,T,T1).?- remove(1,[4,9,8,7,1,9,7,5,1],R).R = [4, 9, 8, 7, 9, 7, 5] Removing an element from a list
اسلاید 11: 11isort([], []).isort([H|T],R):- isort(T,Q), ins(H,Q,R).ins(X, [], [X]).ins(X, [H|T], [H|R]):- X>H, ins(X,T,R).ins(X, [H|T], [X,H|T]):- X=<H.?- isort([4,1,9,5,8,3,2],S).S = [1, 2, 3, 4, 5, 8, 9] ?- isort([a,b,c,d],S).ERROR: Arithmetic: `c/0 is not a functionInsertion Sort
اسلاید 12: 12I/O
اسلاید 13: 13A full-stop must follow a term to be read?- read(X).|: massey.X = massey Yes?- read(X).|: Y.X = _G185 Yes?- read(X).|: likes(john,mary).X = likes(john, mary) Yes?- read(X), name(X,List).|: massey.X = masseyList = [109, 97, 115, 115, 101, 121]
اسلاید 14: 14?- write(hello world).hello worldYes?- write(hello world),nl,nl,tab(9),write(I am here :)).hello world I am here :)Yes?- write(abc).[97, 98, 99]Yes?- write(abc).abcYes
اسلاید 15: 15printlst([ ]) :- put(.), nl.printlst([H|T]) :- write(H), tab(1), printlst(T).?- write([‘This’,is,a,list]).[This, is, a, list]?- printlst([‘This’,is, a,list]).This is a list .?- read(X),nl,write(‘Here is what was entered: ‘),write(X).|: massey.Here is what was entered: masseyX = massey A predicate for printing a list
اسلاید 16: 16male(andrew).male(john). male(george). male(greg). male(adam). female(mary). female(jennifer). female(eve). parents(john,george,mary).parents(greg,adam,eve).parents(jennifer, adam,eve).parents(andrew, adam,eve).is_brother_of(X,Y):-male(X),parents(X, Father, Mother),parents(Y, Father,Mother), X=Y,write(X),tab(1),write(is),tab(1),write(Y),write(s sister.).is_sister_of(X,Y):-female(X),parents(X, Father, Mother),parents(Y, Father, Mother), X=Y,write(X),tab(1),write(is),tab(1),write(Y),write(s sister.).?- is_sister_of(X,Y).jennifer is greg`s sister.X = jenniferY = greg ;jennifer is andrew`s sister.X = jenniferY = andrew
اسلاید 17: 17Built-in predicates “fail” and “true” Fail always fails and true always succeeds?- likes(mary,X).X = john Yes?- likes(mary,X),fail.No?- likes(mary,X),write(X),nl,fail.johnfruitbookNo?- likes(mary,X),write(X),nl,fail ; true.johnFruit ORbookX = _G354 Yeslikes(tom,jerry).likes(mary,john).likes(tom,mouse).likes(tom,jerry).likes(jerry,cheeze).likes(mary,fruit).likes(john,book).likes(mary,book).likes(tom,john).Output predicates do not re-succeed on backtracking
اسلاید 18: 18likes(tom,jerry).likes(mary,john).likes(tom,mouse).likes(tom,jerry).likes(jerry,cheeze).likes(mary,fruit).likes(john,book).likes(mary,book).likes(tom,john).?- likes(mary,X), write(Mary likes ), write(X),put(.), nl, fail.Mary likes john.Mary likes fruit.Mary likes book.No?- likes(mary,X),write(X),nl,fail;write(reached the OR part).johnfruitbookreached the OR partX = _G471 Yes
اسلاید 19: 19write(Enter a number X to be raised to the power of 5 ), read(N),P5 is N**5,write(N),write(‘ to the power of 5 is: ),write(P5).?- write(Enter a number X to be raised to the power of 5: ), read(N),| P5 is N**5,write(N),write( to the power of 5 is: ),write(P5).Enter a number X to be raised to the power of 5:|: 2.2 to the power of 5 is: 32N = 2P5 = 32 Yes?- ?- repeat,write(Enter a number X to be raised to the power of 5: ), | read(N), P5 is N**5,write(N),write( to the power of 5 is: ),| write(P5),fail.Built-in predicate “repeat”
اسلاید 20: 20File I/O
اسلاید 21: 21Prolog accepts input from an input stream send output to an output stream Streams can be files or I/O devicesActive streamsare the keyboard and the screen by default (user)We may only have one stream open for input and one open for output
اسلاید 22: 22tell(Filename) Opens the file named by Filename for writing and makes it the current output stream. It creates the file if it does not exist.telling(X) Retrieves the current input stream.told Closes the file opened by the built-in predicate tell.see(Filename) Opens the file named by Filename for input and makes it the current input straeam.seeing(X) Retrieves the current input stream. seen Closes the file opened by the built-in predicate see.
اسلاید 23: 23?- tell(D:/test.txt).Yes?- telling(X).X = $stream(1996248) Yes?- write(testing tell).Yes?- told.Yestesting tellend_of_fileContents of D:/test.txt?- telling(Old),tell(‘D:/test.txt’),write(‘testing’),told,tell(Old).
اسلاید 24: 24?- tell(‘lksout.txt’),likes(mary,X), write(‘Mary likes ‘),write(X), put(‘.’),nl, fail; told.X = _G662 Yeslikes(tom,jerry).likes(mary,john).likes(tom,mouse).likes(tom,jerry).likes(jerry,cheeze).likes(mary,fruit).likes(john,book).likes(mary,book).likes(tom,john).Mary likes john.Mary likes fruit.Mary likes book.Contents of the file “lks.txt”
اسلاید 25: 25Cut: !Eliminates choicesAlways succeeds but stops backtrackinga:-b,c,!,d.a:-e,f.max(X,Y,Y) :- Y>X.max(X,Y,X). ?- max(1,2,X).X = 2 ;X = 1 ;No?- max(X,Y,Y) :- Y>X, !. max(X,Y,X). ?- max(1,2,X).X = 2 ;No?-
اسلاید 26: 26 Cut makes programs less readable. Using cut can make your programs more efficient. You have to be careful when using cut. Cut, may alter the way your program behaves. When you use cut in a rule, you have to be certain of how your rule will be used. If you are not careful your program may behave strangely.Built-in predicate cut, “!”
اسلاید 27: 27Unexpected results: Using member with cut we only get one value for X, which is not what we expect. member1(X,[X|_]):-!.member1(X,[_|T]):-member1(X,T). ?- trace. Yes[trace] ?- member1(X,[1,2,3,4]). Call: (6) member1(_G401, [1, 2, 3, 4]) ? creep Exit: (6) member1(1, [1, 2, 3, 4]) ? creep X = 1 ; Fail: (6) member1(1, [1, 2, 3, 4]) ? creep NoX = 1 ; X = 2 ; X = 3 ; X = 4 ; NoMember without cut membernocut(X,[X|_]).membernocut(X,[_|T]):-membernocut(X,T). ?- membernocut(X,[1,2,3,4]).
اسلاید 28: 28Efficiency:Using member without cut here, we are wasting time trying out the second part of the predicate when we know that it will fail. Call: (7) membernocut(1, [1, 2, 3, 4]) ? creep Exit: (7) membernocut(1, [1, 2, 3, 4]) ? creepmember succeeded Redo: (7) membernocut(1, [1, 2, 3, 4]) ? creep Call: (8) membernocut(1, [2, 3, 4]) ? creep Call: (9) membernocut(1, [3, 4]) ? creep Call: (10) membernocut(1, [4]) ? creep Call: (11) membernocut(1, []) ? creep Fail: (11) membernocut(1, []) ? creep Fail: (10) membernocut(1, [4]) ? creep Fail: (9) membernocut(1, [3, 4]) ? creep Fail: (8) membernocut(1, [2, 3, 4]) ? creep Fail: (7) membernocut(1, [1, 2, 3, 4]) ? creepNomembernocut(X,[X|_]).membernocut(X,[_|T]):-membernocut(X,T).?- trace.Yes[trace] ?- membernocut(1,[1,2,3,4]),write(member succeeded),fail.
اسلاید 29: 29 Using member with cut: ?- trace. Yes[trace] ?- member1(1,[1,2,3,4]),write(member succeeded),fail. Call: (7) member1(1, [1, 2, 3, 4]) ? creep Exit: (7) member1(1, [1, 2, 3, 4]) ? creepmember succeeded member1(X,[X|_]):-!.member1(X,[_|T]):-member1(X,T).Fail: (7) member1(1, [1, 2, 3, 4]) ? creep No?-
اسلاید 30: 30member(X, [X|T]).member(X, [H|T]) :- not(X=H), member(X, T).Using not instead of cut makes your program more clear member1(X,[X|_]):-!.member1(X,[_|T]):-member1(X,T).
اسلاید 31: 31male(andrew).male(john). male(george). male(greg). male(adam). female(mary). female(jennifer). female(eve). parents(john,george,mary).parents(greg,adam,eve).parents(jennifer, adam,eve).parents(andrew, adam,eve).is_brother_of(X,Y):-male(X),parents(X, Father, Mother),parents(Y, Father,Mother), X=Y.is_sister_of(X,Y):-female(X),parents(X, Father, Mother),parents(Y, Father, Mother),X=Y.?- male(X).X = andrew ;X = john ;X = george ;X = greg ;X = adam ;No?- ?- male(X), ! .X = andrew ;No
اسلاید 32: 32male(andrew).male(john). male(george). male(greg). male(adam). female(mary). female(jennifer). female(eve). parents(john,george,mary).parents(greg,adam,eve).parents(jennifer, adam,eve).parents(andrew, adam,eve).is_brother_of(X,Y):-male(X),!,parents(X, Father, Mother),parents(Y, Father,Mother), X=Y.is_sister_of(X,Y):-female(X),!,parents(X, Father, Mother),parents(Y, Father, Mother),X=Y.
اسلاید 33: 33apend([],L,L):-!.apend([H|T1],L2,[H|T2]):-apend(T1,L2,T2).[trace] ?- apend([],[1,2,3,4],L). Call: (6) apend([], [1, 2, 3, 4], _G409) ? creep Exit: (6) apend([], [1, 2, 3, 4], [1, 2, 3, 4]) ? creepL = [1, 2, 3, 4] ; Fail: (6) apend([], [1, 2, 3, 4], [1, 2, 3, 4]) ? creepNoapend([],L,L).apend([H|T1],L2,[H|T2]):-apend(T1,L2,T2).[trace] ?- apend([],[1,2,3,4],L). Call: (6) apend([], [1, 2, 3, 4], _G409) ? creep Exit: (6) apend([], [1, 2, 3, 4], [1, 2, 3, 4]) ? creepL = [1, 2, 3, 4] ; Fail: (6) apend([], [1, 2, 3, 4], _G409) ? creepNo
اسلاید 34: 34?- tell(‘fam.pl’), listing(male/1), told.Yes male(andrew).male(john).male(george).male(greg).male(adam).Contents of the file famconsult(Filename) :- see(Filename), repeat, read(X), assert(X), X=end_of_file, !, seen. Definition of “consult”H
اسلاید 35: 35male(andrew).male(john). male(george). male(greg). male(adam). female(mary). female(jennifer). female(eve). parents(john,george,mary).parents(greg,adam,eve).parents(jennifer, adam,eve).parents(andrew, adam,eve).?- male(X).X= andrew;X= john;X= george;X= greg;X= adam;?- female(X).X= mary;X= jennifer;X= eve;?- parents(X, adam, eve).X= greg;X= jennifer;X= andrew;?- findall(X, male(X), List).List= [andrew, john, george, greg, adam]?- findall(X, female(X), List).List= [mary, jennifer, eve]?- findall(X, parents(X,adam,eve), List).List= [greg, jennifer, andrew]findall(X,Term,List).
اسلاید 36: 36Other examples?- findall(t(X,Y),parents(X,Y,Z),List).X = _G353Y = _G354Z = _G358List = [t(john, george), t(greg, adam), t(jennifer, adam), t(andrew, adam)] Yes?- ?- findall(t(X,Y),append(X,Y,[a,b]),L).X = _68 Y = _69 L = [t([],[a,b]),t([a],[b]),t([a,b],[])] yes male(andrew).male(john). male(george). male(greg). male(adam). female(mary). female(jennifer). female(eve). parents(john,george,mary).parents(greg,adam,eve).parents(jennifer, adam,eve).parents(andrew, adam,eve).
اسلاید 37: 37call(Goal) Invoke Goal as a goal.?- call(a=a).Yes?- [user].|: likes(mary,john).|: % user compiled 0.02 sec, 152 bytesYes?- call(likes(mary,john)).Yes?- call(likes(mary,X)).X = john Yes?- call(likes(X,Y)).X = maryY = john Yes?- call(likes(X,mary)).No?-
اسلاید 38: 38?- not(likes(mary,john)).No?- not(likes(mary,X)).No?- not(likes(mary,george)).Yes?- not(Goal)Succeeds when Goal fails.Implementation of not using callnot(P):-call(P),!,fail.not(P).
اسلاید 39: 39In Prolog, programs and data are made of terms. A term may be: a constant (an atom or a number) 10, ‘abc’, likes, mary a variable X, Y a compound term likes(mary,john), likes(X,Y).There are several built-in predicates that succeed or fail depending on the type of the term their argument is.atomic(X) Succeeds if X is bound to an atom, a string or anumber (integer or floating point).atom(X)Succeeds if X is bound to an atom.number(X) Succeeds if X is bound to a number (integer or float)float(X) Succeeds if X is bound to a floating point number
اسلاید 40: 40?- atom(a).Yes?- atom(X).No?- X=a,atom(X).X = a Yes?- X=a,atomic(X).X = a Yes?- atomic(a).Yes?- atomic(likes).Yes?- atom(likes).Yes?- atom(1).No?- atom(1.2).No?- atomic(1.2).Yes?- number(5).Yes?- number(1.2).Yes?- float(1).No?- float(1.1).Yes
اسلاید 41: 41An exampleCounting the number of occurances of an atomcount(Atom,List,N).count( _ , [ ] , 0 ).count(Atom, [Atom | Tail] , N):- count(Atom,Tail,N1), N is N1 + 1.count(Atom,[ _ | Tail], N):- count(Atom,Tail,N).?- count(1,[1,2,3,1],N).N = 2 Yes?- count(1,[1,X,Y,Z],N).X = 1Y = 1Z = 1N = 4 % incorrectYes?-?- L= [1,2,3,X,2],write(L),count(2,L,N).[1, 2, 3, _G368, 2]L = [1, 2, 3, 2, 2]X = 2N = 3 % incorrectYes?-
اسلاید 42: 42Solutioncount( _ , [ ] , 0 ).count(Atom,[Head | Tail], N):- atomic(Head), Atom=Head, count(Atom,Tail,N1), N is N1 + 1;count(Atom,Tail,N).?- count(1,[1,2,3,1],N).N = 2 Yes?- count(1,[1,X,Y,Z],N).X = _G269Y = _G272Z = _G275N = 1 Yes?- ?- L= [1,2,3,X,2],write(L),count(2,L,N).[1, 2, 3, _G371, 2]L = [1, 2, 3, _G371, 2]X = _G371N = 2 Yes?-
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