The government saw elected mayors as the key to the unresolved problem of English devolution.

BBC: The flawed concept that saw voters reject city mayors

That is a problem unresolved.

BBC: Eurozone crisis: Troubling year ahead

Of course, so long as Iran fails to meet its obligations, this problem remains unresolved.

WHITEHOUSE: President Obama at 2012 AIPAC Policy Conference

The Iraqi debt problem highlights a huge unresolved flaw in the international financial system.

ECONOMIST: Reconstructing Iraq: Those odious debts | The

We have an opportunity here to deal with a problem that has been with us for a while, and that if left unresolved, poses significant trouble for us in the future.

WHITEHOUSE: Press Briefing