Bridgeland Stability Conditions

14.3. Deformation: DeformedSlicing🔗

14.3.1. deformedSlicing🔗

Deformed slicing (Nodes 7.Q + 7.6 + 7.7). The slicing Q with Q(\psi) = \operatorname{deformedPred}(\sigma, W, \varepsilon, \psi), where \varepsilon < \varepsilon_0 < 1/10 is the perturbation parameter.

Construction: Constructed as a Slicing whose predicate is deformedPred. The closedUnderIso field transports W-semistability across isomorphisms. The shift_iff field uses deformedPred_shift_one and its converse. The hom_vanishing field is Lemma 7.6 via hom_eq_zero_of_deformedPred. The hn_exists field delegates to deformedSlicing_hn_exists.

🔗def
CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} [CategoryTheory.IsTriangulated C] (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) (ε₀ : ) (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) (ε : ) ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) : CategoryTheory.Triangulated.Slicing C
CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} [CategoryTheory.IsTriangulated C] (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) (ε₀ : ) (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) (ε : ) ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) : CategoryTheory.Triangulated.Slicing C

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14.3.2. deformedSlicing_compat🔗

W-compatibility of the deformed slicing. For every nonzero Q-semistable object E of Q-phase \psi, the central charge W([E]) lies on the ray \mathbb{R}_+ \cdot e^{i\pi\psi}.

Proof: The Semistable structure stores \operatorname{wPhaseOf}(W([E]), \alpha) = \psi, which by wPhaseOf_compat gives W([E]) = \|W([E])\| \cdot e^{i\pi\psi} with \|W([E])\| > 0.

🔗theorem
CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing_compat.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) (ε₀ : ) (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) (ε : ) ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) (ψ : ) (E : C) (hQ : (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin).P ψ E) (hE : ¬CategoryTheory.Limits.IsZero E) : m, 0 < m W (CategoryTheory.Triangulated.cl C v E) = m * Complex.exp ((Real.pi * ψ) * Complex.I)
CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing_compat.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) (ε₀ : ) (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) (ε : ) ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) (ψ : ) (E : C) (hQ : (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin).P ψ E) (hE : ¬CategoryTheory.Limits.IsZero E) : m, 0 < m W (CategoryTheory.Triangulated.cl C v E) = m * Complex.exp ((Real.pi * ψ) * Complex.I)

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14.3.3. sigma_semistable_intervalProp🔗

Reverse phase confinement. If E is \sigma-semistable of phase \phi and \|W - Z\|_\sigma < \sin(\pi\varepsilon), then E lies in the Q-interval \mathcal{Q}((\phi - 2\varepsilon - \delta, \phi + 4\varepsilon + \delta)) for any \delta > 0.

Proof: Apply sigmaSemistable_hasDeformedHN to obtain a Q-HN filtration with phases in (\phi - 2\varepsilon, \phi + 4\varepsilon), then widen by \delta.

🔗theorem
CategoryTheory.Triangulated.sigma_semistable_intervalProp.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) {ε₀ : } (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) {ε : } ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) {E : C} {φ : } (hP : σ.slicing.P φ E) (hE : ¬CategoryTheory.Limits.IsZero E) {δ : } ( : 0 < δ) : CategoryTheory.Triangulated.Slicing.intervalProp C (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin) (φ - 2 * ε - δ) (φ + 4 * ε + δ) E
CategoryTheory.Triangulated.sigma_semistable_intervalProp.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) {ε₀ : } (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) {ε : } ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) {E : C} {φ : } (hP : σ.slicing.P φ E) (hE : ¬CategoryTheory.Limits.IsZero E) {δ : } ( : 0 < δ) : CategoryTheory.Triangulated.Slicing.intervalProp C (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin) (φ - 2 * ε - δ) (φ + 4 * ε + δ) E

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14.3.4. deformed_intervalProp_subset_sigma_intervalProp🔗

A Q-interval of radius \varepsilon_0 is contained in a \sigma-interval of radius 2\varepsilon_0: \mathcal{Q}((t - \varepsilon_0, t + \varepsilon_0)) \subseteq \mathcal{P}((t - 2\varepsilon_0, t + 2\varepsilon_0)).

Proof: For each Q-HN factor of an object in \mathcal{Q}((t - \varepsilon_0, t + \varepsilon_0)), phase confinement gives \sigma-phases within \varepsilon of the Q-phase, which lies in (t - \varepsilon_0, t + \varepsilon_0). Since \varepsilon < \varepsilon_0, the \sigma-phases lie in (t - 2\varepsilon_0, t + 2\varepsilon_0).

🔗theorem
CategoryTheory.Triangulated.deformed_intervalProp_subset_sigma_intervalProp.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) {ε₀ : } (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) {ε : } ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) (t : ) : CategoryTheory.Triangulated.Slicing.intervalProp C (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin) (t - ε₀) (t + ε₀) CategoryTheory.Triangulated.Slicing.intervalProp C σ.slicing (t - 2 * ε₀) (t + 2 * ε₀)
CategoryTheory.Triangulated.deformed_intervalProp_subset_sigma_intervalProp.{v, u, u'} (C : Type u) [CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroObject C] [CategoryTheory.HasShift C ] [CategoryTheory.Preadditive C] [ (n : ), (CategoryTheory.shiftFunctor C n).Additive] [CategoryTheory.Pretriangulated C] [CategoryTheory.IsTriangulated C] {Λ : Type u'} [AddCommGroup Λ] {v : CategoryTheory.Triangulated.K₀ C →+ Λ} (σ : CategoryTheory.Triangulated.StabilityCondition.WithClassMap C v) (W : Λ →+ ) (hW : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal 1) {ε₀ : } (hε₀ : 0 < ε₀) (hε₀10 : ε₀ < 1 / 10) (hWide : CategoryTheory.Triangulated.WideSectorFiniteLength C σ ε₀ hε₀ ) {ε : } ( : 0 < ε) (hεε₀ : ε < ε₀) (hsin : CategoryTheory.Triangulated.stabSeminorm C σ (W - σ.Z) < ENNReal.ofReal (Real.sin (Real.pi * ε))) (t : ) : CategoryTheory.Triangulated.Slicing.intervalProp C (CategoryTheory.Triangulated.StabilityCondition.WithClassMap.deformedSlicing C σ W hW ε₀ hε₀ hε₀10 hWide ε hεε₀ hsin) (t - ε₀) (t + ε₀) CategoryTheory.Triangulated.Slicing.intervalProp C σ.slicing (t - 2 * ε₀) (t + 2 * ε₀)

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