question: private void checkNoSelfIntersectingRings ( GeometryGraph graph ) { for ( Iterator i = graph . getEdgeIterator ( ) ; i . hasNext ( ) ; ) { Edge e = ( Edge ) i . next ( ) ; checkNoSelfIntersectingRing ( e . getEdgeIntersectionList ( ) ) ; if ( validErr != null ) return ; } }
target:  Check that there is no ring which self-intersects (except of course at its endpoints). This is required by OGC topology rules (but not by other models such as ESRI SDE, which allow inverted shells and exverted holes).