if (ISVAR (ritem[core[c]]))
bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]]));
+ /* core is sorted on item index in ritem, which is sorted on rule number.
+ Compute itemset with the same sort. */
nitemset = 0;
c = 0;
BITSET_FOR_EACH (iter, ruleset, ruleno, 0)