在Prolog中将Peano数s(N)转换为整数 [英] Convert peano number s(N) to integer in Prolog

问题描述

我在一个教程中遇到了对逻辑数的自然数评估，这让我有些头疼:

I came across this natural number evaluation of logical numbers in a tutorial and it's been giving me some headache:

natural_number(0).
natural_number(s(N)) :- natural_number(N).

该规则粗略地指出:如果N是0，这是自然的；如果不是，我们尝试递归地将s/1的内容发送回该规则，直到内容是0，那么它是自然数如果不是，那么不是.

The rule roughly states that: if N is 0 it's natural, if not we try to send the contents of s/1 back recursively to the rule until the content is 0, then it's a natural number if not then it's not.

因此，我想，我测试了上述逻辑实现，如果我想将s(0)表示为1并将s(s(0))表示为2，则此方法有效，但是我希望能够转换s(0)改为1.

So I tested the above logic implementation, thought to myself, well this works if I want to represent s(0) as 1 and s(s(0)) as 2, but I´d like to be able to convert s(0) to 1 instead.

我想到了基本规则:

sToInt(0,0). %sToInt(X,Y) Where X=s(N) and Y=integer of X

这是我的问题:如何将s(0)转换为1并将s(s(0))转换为2?

So here is my question: How can I convert s(0) to 1 and s(s(0)) to 2?

已回答

编辑:我在实现中修改了基本规则，我接受的答案将其指向了我:

I modified the base rule in the implementation which the answer I accepted pointed me towards:

decode(0,0). %was orignally decode(z,0).
decode(s(N),D):- decode(N,E), D is E +1.

encode(0,0). %was orignally encode(0,z).
encode(D,s(N)):- D > 0, E is D-1, encode(E,N).

所以我现在可以按自己的意愿使用它了，谢谢大家！

So I can now use it like I wanted to, thanks everyone!

推荐答案

这是使用 library(clpfd)

:- use_module(library(clpfd)).

natsx_int(0, 0).
natsx_int(s(N), I1) :-
   I1 #> 0,
   I2 #= I1 - 1,
   natsx_int(N, I2).

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