prolog

问题 I am writing a constraint solver in Prolog that implements a simple logical formula: "(alive(A) and animal(A)) iff (awake(A) or asleep(A))" . I found one way to implement it in Constraint Handling Rules, but it is much more verbose than the original formula: :- use_module(library(chr)). :- chr_constraint is_true/1. is_true(A) \ is_true(A) <=> true. is_true(alive(A)),is_true(animal(A)) ==> is_true(awake(A));is_true(asleep(A)). is_true(awake(A)) ==> is_true(animal(A)),is_true(alive(A)). is_true

问题 The statement : Four couples in all Attended a costume ball. 2 The lady dressed as a cat Arrived with her husband Matt. 3 Two couples were already there, One man dressed like a bear. 4 First to arrive wasn't Vince, But he got there before the Prince. 5 The witch (not Sue) is married to Chuck, Who was dressed as Donald Duck. 6 Mary came in after Lou, Both were there before Sue. 7 The Gipsy arrived before Ann, Neither is wed to Batman. 8 If Snow White arrived after Tess, Then how was each

问题 The statement : Four couples in all Attended a costume ball. 2 The lady dressed as a cat Arrived with her husband Matt. 3 Two couples were already there, One man dressed like a bear. 4 First to arrive wasn't Vince, But he got there before the Prince. 5 The witch (not Sue) is married to Chuck, Who was dressed as Donald Duck. 6 Mary came in after Lou, Both were there before Sue. 7 The Gipsy arrived before Ann, Neither is wed to Batman. 8 If Snow White arrived after Tess, Then how was each

问题 If I have defined all the digits in a Prolog database, such as dig(0), dig(1), ..., dig(9) . What query can I use for Prolog to return the largest digit -- in this case, 9? I tried something like: ?- dig(N), dig(M), N > M. But that just returns the first possibility, not the largest number. 回答1: To find out the largest number you should write an appropriate query, namely one that: Instantiate a digit Checks whether that digit is the largest (i.e. no other digit is larger) So you might want to

问题 I have a set of companies in rank order. I want my rule to check if the companies in a specified list are in rank order, and for the rule to recur until all companies in the list have been checked. I currently have the following: isOrder([]). isOrder([COM1,COM2|T]) :- rank(COM1,D), rank(COM2,E), D<E, print("in order"), isOrder([COM2|T]). However, this does not seem to work. Sometimes, the recursion goes on forever without ending, and sometimes the recursion doesn't work at all. This is when I

问题 [ ] How can I write (using print_path ) a rule to print the path from one node to another if exists Print_path(a, c, Res) ---> Res=[a, f, c] What I did was : path(a,b). %there is a path from a to b path(a,f). path(b,c). path(c,d). path(c,e). path(e,d). path(f,g). path(f,c). path(f,e).` I do not know what to do next. 来源： https://stackoverflow.com/questions/41112132/find-the-shortest-path-between-two-nodes-in-a-graph-in-prolog-and-display-the

问题 I am trying to implement a Prolog predicate that gets a binary tree (represented as t(Left, Root, Right)) and returns a list that is the Maximal Independent Set (MIS) of this tree, and its size. I first understood that MIS(T) is the maximum between the MIS with root and the MIS without the root. Then, I used two theorems, stating that the MIS with root is the unification of the MIS's without the root for all the subtrees, and that MIS without root is the unification of the MIS's of all the

问题 I am trying to implement a Prolog predicate that gets a binary tree (represented as t(Left, Root, Right)) and returns a list that is the Maximal Independent Set (MIS) of this tree, and its size. I first understood that MIS(T) is the maximum between the MIS with root and the MIS without the root. Then, I used two theorems, stating that the MIS with root is the unification of the MIS's without the root for all the subtrees, and that MIS without root is the unification of the MIS's of all the

问题 foo(0,Y,Z) :- Z is Y. foo(X,0,Z) :- Z is X. foo(X,Y,Z) :- X>=Y, M1 is X-2, foo(M1, Y, Zx), Z is Zx + Y. foo(X,Y,Z) :- Y<X, N1 is Y-3, foo(X, N1, Zx), Z is Zx + X. So this is my program and this is what i'm trying to accomplish 𝑓𝑜𝑜(𝑥, 𝑦) = { 𝑥 𝑖𝑓 𝑦 ≤ 0 𝑦 𝑖𝑓 𝑥 ≤ 0 𝑥 + 𝑓𝑜𝑜(𝑥 − 2, 𝑦) 𝑖𝑓 𝑥 ≥ 𝑦 𝑦 + 𝑓𝑜𝑜(𝑥, 𝑦 − 3) 𝑖𝑓 𝑥 < 𝑦 } Why does my program not output anything? This is what i think i'm saying - If X = 0, foo(0,Y,Z), than return Z as Y. If Y = 0, foo(0,Y,Z), than return Z as X. if X>=Y, than do

问题 I have a List L with some terms like range(2,3), where the first element is the term with the lowest Y, now I need to sort the other elements of the list L (the first element will remain unchanged), I need to sort them by polar angle in counterclockwise order. If polar angle of two points is same, then I need to put the nearest term first. I defined the predicate angle2d/2: angle2d(A, B, R) :- A =.. [_,Ax,Ay], B =.. [_,Bx,By], R is atan2((Ay-By),(Ax-Bx)). that give me the counter clockwise