elk-reasoner/src/main/java/org/semanticweb/elk/reasoner/Reasoner.java
public synchronized Set<? extends Node<ElkClass>> getSuperClassesQuietly(
			ElkClassExpression classExpression, boolean direct)
			throws ElkException {
		try {
			return getSuperClasses(classExpression, direct);
		} catch (final ElkInconsistentOntologyException e) {
			// All classes are equivalent to each other, so also to owl:Nothing.
			final TaxonomyNode<ElkClass> node = getTaxonomyQuietly()
					.getBottomNode();
			return direct ? node.getDirectSuperNodes()
					: node.getAllSuperNodes();
		}
	}
public synchronized Set<? extends Node<ElkClass>> getSuperClassesQuietly(
			ElkClassExpression classExpression, boolean direct)
			throws ElkException {
		try {
			return getSuperClasses(classExpression, direct);
		} catch (final ElkInconsistentOntologyException e) {
			// All classes are equivalent to each other, so also to owl:Nothing.
			final TaxonomyNode<ElkClass> node = getTaxonomyQuietly()
					.getBottomNode();
			return direct ? node.getDirectSuperNodes()
					: node.getAllSuperNodes();
		}
	}
Return the (direct or indirect) superclasses of the given
{@link ElkClassExpression} as specified by the parameter. The method
returns a set of {@link Node}s, each of which representing an equivalent
class of superclasses. Calling of this method may trigger the computation
of the taxonomy, if it has not been done yet.

@param classExpression
the {@link ElkClassExpression} for which to return the
superclass {@link Node}s
@param direct
if {@code true}, only direct superclasses are returned
@return the set of {@link Node}s for direct or indirect superclasses of
the given {@link ElkClassExpression} according to the specified
parameter
@throws ElkException
if the result cannot be computed