Why connectedness is hard to compute
	• Even for simple line drawings, there are exponentially many cases. • Removing one segment can break connectedness – But this depends on the precise arrangement of the other pieces. – Unlike parity, there are no simple summaries of the other pieces that tell us what will happen. • Connectedness is easy to compute with an iterative algorithm. – Start anywhere in the ink – Propagate a marker – See if all the ink gets marked.