+ class Position implements IntegerMappable {
+
+ public int ord = -1;
+ public int compareTo(Position p, Walk.Cache cache) {
+ Position position = this;
+ Position rposition = p;
+ int ret = 0;
+ if (Reduction.canKill(cache, position, rposition) &&
+ Reduction.canKill(cache, rposition, position)) throw new Error();
+ if (Reduction.canKill(cache, position, rposition)) ret = 1;
+ else if (Reduction.canKill(cache, rposition, position)) ret = -1;
+ if (Reduction.canNeed(cache, position, rposition)) ret = 1;
+ else if (Reduction.canNeed(cache, rposition, position)) ret = -1;
+ return ret;
+ }