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Atlas.TensorCategories.code.QuasiTensorFunctor

Definition 1.14.1 (Etingof–Gelaki–Nikshych–Ostrik): A quasi-tensor functor between abelian monoidal categories C and D over a field k. It consists of an exact (mono- and epi-preserving) faithful functor F equipped with natural isomorphisms J X Y : F X ⊗ F Y ≅ F (X ⊗ Y) and a unit isomorphism F (𝟙_ C) ≅ 𝟙_ D.

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    Definition 1.14.1 (Etingof–Gelaki–Nikshych–Ostrik): A tensor functor between abelian monoidal categories C and D over a field k is an exact faithful functor F equipped with a monoidal structure (coherent associativity and unit isomorphisms).

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      Every tensor functor is in particular a quasi-tensor functor: the monoidal structure provides the natural isomorphisms J and the unit isomorphism.

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        @[reducible, inline]

        Reference abbreviation for Definition 1.14.1: a quasi-tensor functor.

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          @[reducible, inline]

          Reference abbreviation for Definition 1.14.1: a tensor functor.

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            A quasi-tensor functor whose underlying functor carries a monoidal structure upgrades to a tensor functor.

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              Definition 1.19.1 (Etingof–Gelaki–Nikshych–Ostrik): A quasi-fiber functor on an abelian monoidal category C over a field k is a quasi-tensor functor from C to the category of k-modules.

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                Definition 1.19.1 (Etingof–Gelaki–Nikshych–Ostrik): A fiber functor on an abelian monoidal category C over a field k is a tensor functor from C to the category of k-modules.

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                  @[reducible, inline]

                  Reference abbreviation for Definition 1.19.1: a quasi-fiber functor.

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                    @[reducible, inline]

                    Reference abbreviation for Definition 1.19.1: a fiber functor.

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                      A fiber functor on C is in particular a tensor functor from C to the category of k-modules.

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                        A fiber functor is in particular a quasi-fiber functor, via its monoidal structure.

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                          A tensor functor from C to the category of k-modules is a fiber functor on C.

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                            Exhibit a quasi-fiber functor as a quasi-tensor functor into the category of k-modules.

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                              Definition 1.34.1 (Etingof–Gelaki–Nikshych–Ostrik): A quasi-fiber functor QFF is normalized when the natural isomorphisms J are compatible with the left and right unit constraints via the unit isomorphism.

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                                @[reducible, inline]

                                Reference abbreviation for Definition 1.34.1: a normalized quasi-fiber functor.

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                                  @[reducible, inline]

                                  Reference abbreviation for Definition 1.34.1.

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                                    Definition 1.34.2 (Etingof–Gelaki–Nikshych–Ostrik): Two quasi-fiber functors on C are twist-equivalent if they share the same underlying functor.

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                                      The twist isomorphism on QFF₁.F X ⊗ QFF₁.F Y obtained from a twist-equivalence h : QFF₁.TwistEquivalent QFF₂, comparing the two natural isomorphisms J on the same underlying functor.

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                                        @[reducible, inline]

                                        Reference abbreviation for Definition 1.34.2: twist-equivalence of quasi-fiber functors.

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                                          An object P of an abelian category C is a projective generator if it is projective and detects zero objects (any X admitting only the zero map from P must itself be zero).

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                                            Every finite abelian k-linear category with enough projectives admits a projective generator.

                                            A finite rigid k-linear monoidal category over an algebraically closed field with End(𝟙) ≃ₐ[k] k and a projective generator P admits a fiber functor.

                                            The endomorphism algebra of a fiber functor on a finite rigid k-linear monoidal category over an algebraically closed field carries a Hopf algebra structure.

                                            Every finite-dimensional Hopf algebra H over an algebraically closed field arises as the endomorphisms of a fiber functor on some finite rigid k-linear monoidal category.

                                            Any two exact faithful k-linear functors from a finite abelian monoidal category to the category of k-modules are naturally isomorphic.

                                            Proposition 1.34.7 (Etingof–Gelaki–Nikshych–Ostrik): On a finite abelian k-linear monoidal category, any two quasi-fiber functors are naturally isomorphic on the underlying functors; equivalently, a quasi-fiber functor is unique up to twisting.

                                            @[reducible, inline]

                                            Reference abbreviation for Definition 1.14.1: a quasi-tensor functor.

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                                              @[reducible, inline]

                                              Reference abbreviation for Definition 1.14.1: a tensor functor.

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                                                @[reducible, inline]

                                                Reference abbreviation for Definition 1.14.1.

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                                                  @[reducible, inline]

                                                  Reference abbreviation for Definition 1.19.1: a quasi-fiber functor.

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                                                    @[reducible, inline]

                                                    Reference abbreviation for Definition 1.19.1: a fiber functor.

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                                                      @[reducible, inline]
                                                      abbrev Definition_1_19_1 (k : Type u_1) [Field k] (C : Type u_2) [CategoryTheory.Category.{u_3, u_2} C] [CategoryTheory.MonoidalCategory C] [CategoryTheory.Abelian C] :
                                                      Type (max (max u_2 u_3) (u_1 + 1))

                                                      Reference abbreviation for Definition 1.19.1.

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