code: public boolean removeRelation(
              TemporalExtendedPropositionDefinition lhsRule,
              TemporalExtendedPropositionDefinition rhsRule) {
          List<TemporalExtendedPropositionDefinition> key = Arrays.asList(
                  lhsRule, rhsRule);
          if (defPairsMap.remove(key) != null) {
              return true;
          } else {
              return false;
          }
      }
docs: Removes a relation between two temporal extended proposition definitions.
  
  @param lhsRule
  a {@link TemporalExtendedPropositionDefinition}.
  @param rhsRule
  a {@link TemporalExtendedPropositionDefinition}.
  @return <code>true</code> if removing the relation was successful,
  <code>false</code> otherwise (e.g., if either argument is
  <code>null</code>, the arguments are not part of this
  abstraction definition, or if no relation was set for them).