/**
* Checks if there is a dependency of 'a' on 'b', i.e., whether 'b' is reachable from 'a' in the
* graph representation of the current assignment. It is important that the current assignment is
* acyclic; otherwise, this implementation might not terminate.
*
* @param a the start variable
* @param b the goal variable
* @return true iff 'a' depends on 'b'
*/
boolean dependsOn(Atom a, Atom b) {
for (Atom at : getSubsumers(a)) {
if (!at.isGround()) {
Atom nextVar = at.getConceptName();
if (nextVar.equals(b)) {
return true;
}
if (dependsOn(nextVar, b)) {
return true;
}
}
}
return false;
}
/**
* Checks if a new assignment would make this assignment cyclic.
*
* @param var the variable index
* @param at the new atom
* @return true iff the resulting assignment would be cyclic
*/
public boolean makesCyclic(Atom var, Atom at) {
if (at.isGround()) return false;
Atom conceptName = at.getConceptName();
if (conceptName.equals(var)) return true;
return dependsOn(conceptName, var);
}