refreshing

reasoning/kaprekar-constant/kaprekar-constant-query.n3

@@ -2,7 +2,8 @@
 @prefix : <https://eyereasoner.github.io/ns#>.
 
 {
-    10000 log:repeat ?I.
+    ("consult" "./kaprekar-constant.pl") log:program true.
+    ("between" 0 9999 ?I) log:program true.
     ?I :recursionCount ?N.
 } => {
     ?I :recursionCount ?N.

reasoning/kaprekar-constant/kaprekar-constant.pl

@@ -0,0 +1,33 @@
+% Kaprekar's constant
+
+% recursive case till 6174 is reached
+'<https://eyereasoner.github.io/ns#kaprekar-constant>'(A, B, C) :-
+    A =\= 0,
+    '<https://eyereasoner.github.io/ns#numberToDigits>'(A, D),
+    keysort(D, E),
+    reverse(E, F),
+    '<https://eyereasoner.github.io/ns#digitsToNumber>'(E, G),
+    '<https://eyereasoner.github.io/ns#digitsToNumber>'(F, H),
+    I is H-G,
+    J is B+1,
+    (   I =:= 6174
+    ->  C = J
+    ;   '<https://eyereasoner.github.io/ns#kaprekar-constant>'(I, J, C)
+    ).
+
+% convert 4 digit number to digits
+'<https://eyereasoner.github.io/ns#numberToDigits>'(A, [B-0, C-0, D-0, E-0]) :-
+    B is A // 1000,
+    F is A rem 1000,
+    C is F // 100,
+    G is F rem 100,
+    D is G // 10,
+    E is G rem 10.
+
+% convert 4 digits to number
+'<https://eyereasoner.github.io/ns#digitsToNumber>'([A-0, B-0, C-0, D-0], E) :-
+    E is A*1000+B*100+C*10+D.
+
+% recursion count
+'<https://eyereasoner.github.io/ns#recursionCount>'(I, J) :-
+    '<https://eyereasoner.github.io/ns#kaprekar-constant>'(I, 0, J).

reasoning/kaprekar-constant/test

@@ -1,2 +1,2 @@
 #!/bin/bash
-eye --quiet --skolem-genid 8b98b360-9a70-4845-b52c-c675af60ad01 --wcache https://eyereasoner.github.io/eye/reasoning .. --nope https://eyereasoner.github.io/eye/reasoning/kaprekar-constant/kaprekar-constant.n3 --query https://eyereasoner.github.io/eye/reasoning/kaprekar-constant/kaprekar-constant-query.n3 --output kaprekar-constant-answer.n3
+eye --quiet --skolem-genid 8b98b360-9a70-4845-b52c-c675af60ad01 --wcache https://eyereasoner.github.io/eye/reasoning .. --nope --query https://eyereasoner.github.io/eye/reasoning/kaprekar-constant/kaprekar-constant-query.n3 --output kaprekar-constant-answer.n3