if (sg.getUsageLink(focus, node) != null) { return (true);
if (sg.getUsageLink(node, focus) != null) { continue;
UsageLink existingul=sg.getUsageLink(sn, tsn);
if (sg.getUsageLink(focus, node) != null) { return (true);
if (sg.getUsageLink(node, focus) != null) { continue;
UsageLink existingul=sg.getUsageLink(sn, tsn);