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Mathlib.CategoryTheory.Triangulated.Orthogonal

Orthogonal of triangulated subcategories #

Let P be a triangulated subcategory of a pretriangulated category C. We show that P.rightOrthogonal (which consists of objects Y with no nonzero map X ⟶ Y with X satisfying P) is a triangulated subcategory. The dual result for P.leftOrthogonal is also obtained.