ATermAppl notC2 = ATermUtils.negate( c2 );
ATermAppl c = ATermUtils.makeAnd( c1, notC2 );
Timer t = kb.timers.startTimer( "subClassSat" );
boolean sub = !isSatisfiable( c, false );
t.stop();
if( log.isLoggable( Level.FINE ) ) {
log.fine( " Result: " + sub + " (" + t.getLast() + "ms)" );
}