A.Θεωρία Οπισθοδρόμηση Μη προσδοκώμενα αποτελέσματα Το κατηγόρημα ! /0 Βίαιος Τερματισμός Προγράμματος Το κατήγορημα fail / 0 B.Ασκήσεις

1. 31
PROLOG
5:
!"# $%&' ( ) '
!
" # # $ % #
& '()* !
+ , & #
. !
1.
1. "# $
% " !& $ ' # :
!"# $%&' ( ) '
(" " :
max(X,Y,M):-
X>Y,
M=X.
max(X,Y,M):-
X=<Y,
M=Y.
?- max(4,5, ).
" ! " " " !
?- max(4,5, ).
= 5.
?- max(5,4, ).
= 5 ;
false.
. !
1.
1. "# $
) ! * + ! * * $ " $
:
*!"# $%&' ( ) '
: max(4,5, ).
max(X,Y,M):-
X>Y,
M=X.
max(X,Y,M):-
X=<Y,
M=Y.
: max(4,5, ).
: 4>5, =4.
X=4, =5, = X=4, =5, =
: 4=<5, =5.
?- max(4,5,N).
N = 5.
: =5.
: N=5
?- max(5,4,N).
N = 5 ;
false.
: max(5,4, ).
: 5=<4, =4.
X=5, =4, =
false
X=5, =4, =
: 5>4, =5.
: =5.
: N=5

2. . !
1.
2. To " ! / 0
% " ! / 0 ( + & cut) ! $
:
!"# $%&' ( ) '
:
" $ * * .
$ , . - * ! "
, * !
% !& * , * $
* $ ! ! *
! " .
# * * " max ' :# * * " max ' :
max(X,Y,M):-
X>Y,!,
M=X.
max(X,Y,M):-
X=<Y,
M=Y.
. !
1.
2. To " ! / 0
. $ * " $ * " $
+!"# $%&' ( ) '
: max(4,5, ).
max(X,Y,M):-
X>Y,!,
M=X.
max(X,Y,M):-
X=<Y,
M=Y.
: 4>5,!, =4.
X=4, =5, = X=4, =5, =
: 4=<5, =5.
?- max(4,5,N).
N = 5.
: =5.
: N=5
: max(5,4, ).
X=5, =4, =X=5, =4, =
?- max(5,4,N).
N = 5.: 5=<4, =4.
X=5, =4, =X=5, =4, =
: 5>4,!, =5.
: =5.
: N=5
: !, =5.
. !
1.
2. To " ! / 0
* ! $ * " /$
.
,!"# $%&' ( ) '
.
0 * ! # * " if-else
1 * ! * " :
max(X,Y,M):-
X>Y,!,
M=X.
max(X,Y,M):-
max(X,Y,M):-
X>Y,!,
M=X.
max(X,Y,M):-
max(X,Y, ):-
X>Y,!.
max(X,Y, ).
max(X,Y,M):-
X=<Y,
M=Y.
max(X,Y,M):-
M=Y.
max(X,Y, ).
. !
2. . ! %
1. To " fail / 0
% " fail / 0 ! " * ! :
-!"# $%&' ( ) '
" $ * * .
( "" )
* " " .
2 $ * " * " # ! fail
!& * * ! * .
(! ! & " + ! *
$ ! * " $ *
" .

3. .. "
(, 1
" Prolog:
.!"# $%&' ( ) '
first:- room(X),
write(X),
nl,
fail.
0 ! " :
(a1) first.
(a2) second.fail.
second:- room(X),
!,
write(X),
nl,
fail.
third:- room(X),
write(X),
nl,
!,
fail.
fourth:- !,
room(X),
write(X),
(a2) second.
(a3) third.
(a4) fourth.
(a5) fifth.
) " $ ! !
" :
(1) (2) (3) (4) (5)
a a
b
a a
b
a
b
write(X),
nl,
fail.
fifth:- room(X),
write(X),
nl,
fail,
!.
room(a).
room(b).
room(c).
room(d).
) / , & * , . . a3->2
No c
d
No
No c
d
No
c
d
No
.. "
(, 1
/!"# $%&' ( ) '
!"# $%&' ( ) '
.. "
(, 2
( ) f(X,Y):- X<0,!, Y=0.
( )
f(X,Y):- X<0,!, Y=0.
f(_,0).
( )
f(X,Y):- X>=0, !, Y=0.
f(_,1).
( )
f(X,Y):- X<0, !, Y=0.
f(_,1).
( )
f(_,1).
f(X,Y):- X<0, !, Y=0.
.. "
(, 2
!"# $%&' ( ) '