Let $f:X\to Y$ be a morphism of schemes. When is the direct image functor $f_\ast:\mathbf{Shv}(\mid X\mid) \to \mathbf{Shv}(\mid Y\mid)$ faithful, full, or essentially surjective?
Hints and references would be appreciated.
2026-03-31 20:33:27.1774989207
Faithful direct image functor
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