It necessitates continuous innovation.

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"As much as Baghdad might like to object, economy (sic) reality necessitates that it go along with the Kurds -- for now, " wrote Joost Hiltermann, an Iraq expert with the International Crisis Group, in a recent article on Foreign Policy.com.

CNN: Iraqi Kurds begin exporting oil

Contrast that with the NBA. It plays indoors, of course, which necessitates smaller venues.

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Climbing the six Abels in the brutal Western Arthurs Range, located inside the World Heritage-listed Tasmanian Wilderness Area that covers 20% of the island, necessitates a walk through such difficult mountain terrain that it can take walkers up to two weeks to hike what is often described as the most difficult bushwalk in Australia.

BBC: Tasmania's greatest mountain quest