fix: queens

B/nqueens.lp

@@ -1,4 +1,5 @@
-#const n = 8.
+#const n = 20.
+#const k = 5.
 
 % n-Queens encoding
 
@@ -6,3 +7,4 @@
 { q(1..n,J) } == 1 :- J = 1..n.
 :- { q(D-J,J) } >= 2, D =   2..2*n.
 :- { q(D+J,J) } >= 2, D = 1-n..n-1.
+:- q(X1, Y1), q(X2, Y2), X1 != X2, |X1-X2| + |Y1-Y2| < k.

C/nqueens.idp

@@ -10,10 +10,10 @@ vocabulary V {
 }
 
 structure S : V {
-        index = {1..4}
-        diag = {1..7}
-        n = 4
-    	k = 2
+        index = {1..20}
+        diag = {1..39}
+        n = 20
+    	k = 5
 }
 
 theory T : V {
@@ -23,8 +23,8 @@ theory T : V {
         !y : ?=1x : queen(x, y).                                //(2)
         !d : #{x y : queen(x, y) & diag1(x, y) = d} < 2.        //(3)
         !d : #{x y : queen(x, y) & diag2(x, y) = d} < 2.        //(4)
-    	~? x1 y1 x2 y2: queen(x1, y1) & queen(x2, y2) & ~x1 = x2 & abs(x1-x2) + abs(y1-y2) =< k.
-    	//~? x1 y1 x2 y2: queen(x1, y1) & queen(x2, y2) & abs(x1-y1) = 3.
+    	!x1 y1 x2 y2: queen(x1, y1) & queen(x2, y2) & x1 ~= x2 => abs(x1-x2) + abs(y1-y2) >= k.
+        //~? x1 y1 x2 y2: queen(x1, y1) & queen(x2, y2) & ~x1 = x2 & abs(x1-x2) + abs(y1-y2) =< k.
     	}
 
 procedure main() {

randomgen.py

@@ -1,5 +1,6 @@
 import random
-for i in range(100000):
-    j = random.randint(1,10000)
-    k = random.randint(1,10000)
+x = int(input())
+for i in range(10 * x):
+    j = random.randint(1,x)
+    k = random.randint(1,x)
     print("edge(", j, ",", k, ").")