在 Prolog 中，如何对用符号和谓词链表示的偶数和奇数进行排序？

Question

标题可能比较模糊，直接看代码

number(one, odd).
number(two, even).
number(three, odd).
number(four, even).
number(five, odd).

greaterThan(five, four).
greaterThan(four, three).
greaterThan(three, two).
greaterThan(two, one).

if_larger(A,B):- elder_than(A,B).
if_larger(A,B):- elder_than(A,X),greaterThan(X,B).

even(A):- number(A, even).
odd(A):- number(A, odd).

largest(A):-
    not(greaterThan(_,A)).

largestEven(A):-
    even(A),
    not((if_larger(X,A), even(X))).

largestOdd(A):-
    odd(A),
    not((if_larger(X,A), odd(X))).

如何按以下顺序对数字进行排序：一、三、五、二、四。

我认为解决方案应该是下面的形式，但是我想不出来。

next(A, Next):- 
    odd(A), odd(Next),
    ...

next(A, Next):- 
    even(A), even(Next),
    ...

next(A, Next):- 
    odd(A), even(Next),
    ...

或者，是否可以生成一个列表，例如[一、三、五、二、四]。

Answer 1

我会回答我自己的问题。这个想法是使用 final/3 构建所有数字的列表，然后对数字列表应用插入排序。

实施

number(five, odd).
number(one, odd).
number(two, even).
number(three, odd).
number(four, even).

greaterThan(five, four).
greaterThan(four, three).
greaterThan(three, two).
greaterThan(two, one).

even(A):- number(A, even).
odd(A):- number(A, odd).

is_larger(A,B):- greaterThan(A,B).
is_larger(A,B):- greaterThan(A,X),is_larger(X,B).

% the order considered even and odd
% which is odd before even, small before large
in_order(A,B):- odd(A), even(B).
in_order(A,B):- odd(A), odd(B), is_larger(B,A).     % smaller numbers comes first
in_order(A,B):- even(A), even(B), is_larger(B,A).   % smaller numbers comes first


% apply insertion sort on A 
insertion_sort(A,B):- sort_helper(A, [], B).
sort_helper([], OldList, OldList).
sort_helper([H|T], OldList, Result):- insert(H, OldList, NewList), sort_helper(T, NewList, Result).

% insert(A,L,Result) put A into L 
insert(A, [], [A]).
insert(A, [H|T], [A,H|T]):- in_order(A,H).
insert(A, [H|T], [H|NewList]):- not(in_order(A,H)), insert(A, T, NewList).

% Interface
oddEvenSortedList(OddEvenSortedList):- findall(A, number(A,_), Numbers), insertion_sort(Numbers, OddEvenSortedList).

结果

?- ['number.pl'].
true.

?- oddEvenSortedList(OddEvenSortedList).
OddEvenSortedList = [one, three, five, two, four].

这道题实际上是我学校作业的修改版。最初的问题是 Prolog 中的 Royal Family Succession。问了很多朋友怎么解决这个问题，终于得到了这个解决方案。我也会post原来的问题。

The old Royal succession rule states that the throne is passed down along the male line according to the order of birth before the consideration along the female line – similarly according to the order of birth. Queen Elizabeth, the monarch of United Kingdom, has four offsprings; namely:- Prince Charles, Princess Ann, Prince Andrew and Prince Edward – listed in the order of birth.

在 Prolog 中，如何对用符号和谓词链表示的偶数和奇数进行排序？

In Prolog, how to sort even and odd numbers represented with symbols and chains of predicates?

knowledge-management

prolog