Purdue University economists conclude in a new study that an EPA waiver of the ethanol requirement for gasoline - sought by livestock producers and four governors - won’t guarantee lower corn prices. Purdue researchers argue in their study the impact of an EPA partial waiver of the Renewable Fuels Standard on corn prices all depends on what refiners do. And that depends on many factors - including the price of oil - use of blending credits from prior years - so-called rins - and an easing of the drought. Purdue Economics Professor Wally Tyner…