# Some 'weak proper and smooth base change' theorems for Nisnevich sheaves?

Among the most important tools for studying etale cohomology are the proper and smooth base change theorems. I suspect that these theorems are no longer true for Nisnevich cohomology (probably finite morphisms of fields may already give counterexamples). Yet are there some classes of morphisms of varieties for which certain Nisnevich analogues of the base change theorems are known?

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