StandardSubspaceModular · section of the QIQT-H book

QIQTH.StandardSubspaceModular

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StandardSubspaceModular · entries 753–807 of 1000

Definition 753 (projK).  source ↗

RvD P — the real-orthogonal projection onto the standard subspace 𝒦.

PHS  :=  (S.cl).starProjectionP\,H\,S \;:=\; (S.\mathrm{cl}).\mathrm{starProjection}

Used by oneParticleBW_niceWedge, h1_of_stripKMSrvd, comparisonDatum_of_gConstancy, gConstancy_of_inputs, oneParticleBW_of_inputs, oneParticleBW_of_stripKMSrvd_density, oneParticleBW_complete, oneParticleBW_wedge_complete, and 51 more.

Definition 754 (projIK).  source ↗

RvD Q — the real-orthogonal projection onto i𝒦 = mulI 𝒦.

QHS  :=  (S.cl.mulI).starProjectionQ\,H\,S \;:=\; (S.\mathrm{cl}.\mathrm{mulI}).\mathrm{starProjection}

Used by ComparisonDatum, oneParticleBW_of_comparison, comparisonDatum_of_gConstancy, modUnitary_eq_of_orbit_compare, rvdR, projIK_idem, rvdR_apply, rvdR_inner_self, and 28 more.

Definition 755 (rvdR).  source ↗

RvD R = P + Q (Definition 2.1).

RHS  :=  PS+QSR\,H\,S \;:=\; \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S + \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S

Used by rvdR_apply, rvdR_inner_self, rvdR_inner_self_nonneg, rvdR_inner_self_le, rvdR_inner_symm, rvdR_eq_zero, rvdR_smul_I, rvdR_smul_complex, and 23 more.

Lemma 756 (projK_idem).  source ↗

P is idempotent (a projection).

IsIdempotentElem(PS)\mathrm{IsIdempotentElem}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)

Proof. Immediate from the definitions. \square

Used by rvdRC_mul_rvdTwoSubRC_apply, rvdPmQ_mul_rvdR, rvdSqrtR_range_dense_in_K.

Lemma 757 (projIK_idem).  source ↗

Q is idempotent (a projection).

IsIdempotentElem(QS)\mathrm{IsIdempotentElem}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)

Proof. Immediate from the definitions. \square

Used by rvdRC_mul_rvdTwoSubRC_apply, rvdPmQ_mul_rvdR, eq_of_mem_K_of_inner_perp_IK.

Lemma 758 (rvdR_apply).  source ↗

(RS)ξ=(PS)ξ+(QS)ξ(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi = (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)\,\xi + (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)\,\xi

Proof. Immediate from the definitions. \square

Used by rvdR_inner_self, rvdR_smul_I, rvdPmQ_eq_zero, modConj_projIK_modConj, modConj_projK_modConj.

Lemma 759 (rvdR_inner_self).  source ↗

RvD Prop 2.2(1), key identity: ⟪R ξ, ξ⟫ = ‖P ξ‖² + ‖Q ξ‖². (Each projection is self-adjoint idempotent, so ⟪P ξ, ξ⟫ = ‖P ξ‖².) This is the quadratic form whose vanishing forces P ξ = Q ξ = 0, the crux of R’s injectivity and hence of the well-definedness of the modular operator.

(RS)ξ,ξ=(PS)ξ2+(QS)ξ2\langle {(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi},{\xi}\rangle = {\|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)\,\xi\|}^{2} + {\|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)\,\xi\|}^{2}

Proof. By rvdR_apply. \square

Used by rvdR_inner_self_nonneg, rvdR_inner_self_le, rvdR_eq_zero.

Lemma 760 (rvdR_inner_self_nonneg).  source ↗

0 ≤ ⟪R ξ, ξ⟫ — the lower half of RvD’s 0 ≤ R ≤ 2.

0(RS)ξ,ξ0 \le \langle {(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi},{\xi}\rangle

Proof. By projK, projIK, rvdR_inner_self. \square

Used by rvdRC_isPositive.

Lemma 761 (norm_projK_apply_le).  source ↗

P is a contraction: ‖P ξ‖ ≤ ‖ξ‖.

(PS)ξξ\|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)\,\xi\| \le \|\xi\|

Proof. Immediate from the definitions. \square

Used by rvdR_inner_self_le.

Lemma 762 (norm_projIK_apply_le).  source ↗

Q is a contraction: ‖Q ξ‖ ≤ ‖ξ‖.

(QS)ξξ\|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)\,\xi\| \le \|\xi\|

Proof. Immediate from the definitions. \square

Used by rvdR_inner_self_le.

Lemma 763 (rvdR_inner_self_le).  source ↗

⟪R ξ, ξ⟫ ≤ 2‖ξ‖² — the upper half of RvD’s 0 ≤ R ≤ 2 (each projection is a contraction, so ‖P ξ‖² + ‖Q ξ‖² ≤ 2‖ξ‖²).

(RS)ξ,ξ2ξ2\langle {(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi},{\xi}\rangle \le 2 \cdot {\|\xi\|}^{2}

Proof. By projK, projIK, rvdR_inner_self, norm_projK_apply_le, norm_projIK_apply_le. \square

Used by rvdR_le_two.

Lemma 764 (rvdR_inner_symm).  source ↗

R is symmetric (self-adjoint in the inner-product sense): ⟪R x, y⟫ = ⟪x, R y⟫. Each projection P, Q is self-adjoint (inner_starProjection_left_eq_right). (The stronger operator-level statement IsSelfAdjoint (rvdR S)star R = R — is rvdR_isSelfAdjoint below, available now that open ClosedSubmodule supplies InnerProductSpace ℝ H and hence the adjoint/Star on H →L[ℝ] H.)

(RS)x,y=x,(RS)y\langle {(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,x},{y}\rangle = \langle {x},{(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,y}\rangle

Proof. Immediate from the definitions. \square

Used by rvdRC_isSymmetric, rvdR_le_two.

Lemma 765 (rvdR_eq_zero).  source ↗

RvD Prop 2.2(1): R is injective. If R ξ = 0 then ⟪R ξ, ξ⟫ = 0, so by rvdR_inner_self both ‖P ξ‖ = ‖Q ξ‖ = 0; hence ξ ⊥ 𝒦 and ξ ⊥ i𝒦, i.e. ξ ∈ 𝒦ᗮ ⊓ (i𝒦)ᗮ = (𝒦 ⊔ i𝒦)ᗮ = ⊤ᗮ = ⊥ using S.IsCyclic (𝒦 + i𝒦 dense). Injectivity of R is what makes the modular operator well-defined.

(RS)ξ=0ξ=0(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi = 0 \to \xi = 0

Proof. By projK, projIK, rvdR_inner_self. \square

Used by rvdPmQ_eq_zero.

Lemma 766 (projK_isSelfAdjoint).  source ↗

P is self-adjoint as a bounded operator (star (projK S) = projK S).

IsSelfAdjoint(PS)\mathrm{IsSelfAdjoint}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)

Proof. Immediate from the definitions. \square

Used by rvdPmQ_isSelfAdjoint.

Lemma 767 (projIK_isSelfAdjoint).  source ↗

Q is self-adjoint as a bounded operator.

IsSelfAdjoint(QS)\mathrm{IsSelfAdjoint}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)

Proof. Immediate from the definitions. \square

Used by rvdPmQ_isSelfAdjoint, inner_real_of_mem_K_perp_IK.

Lemma 768 (projIK_smul_I).  source ↗

Conjugation identity (1): Q(i·ξ) = i·(P ξ) (projIK = J·projK·J⁻¹, J = mult-by-i). Proved by the variational characterization: i·(P ξ) ∈ i𝒦, and i·ξ − i·(P ξ) = i·(ξ − P ξ) is ⊥ᵣ i𝒦 because mult-by-i is an isometry and ξ − P ξ ⊥ᵣ 𝒦.

(QS)(iξ)=i(PS)ξ(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)\,(i \cdot \xi) = i \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)\,\xi

Proof. Immediate from the definitions. \square

Used by projK_smul_I, rvdR_smul_I, rvdPmQ_smul_I, modConj_smul_I, inner_real_of_mem_K_perp_IK.

Lemma 769 (projK_smul_I).  source ↗

Conjugation identity (2): P(i·ξ) = i·(Q ξ). Algebraic consequence of (1) (projIK_smul_I) via i·(i··) = −·.

(PS)(iξ)=i(QS)ξ(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S)\,(i \cdot \xi) = i \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S)\,\xi

Proof. By projIK_smul_I. \square

Used by rvdR_smul_I, rvdPmQ_smul_I, modConj_smul_I.

Lemma 770 (rvdR_smul_I).  source ↗

R = P + Q is ℂ-linear: R(i·ξ) = i·(R ξ). Combines the two conjugation identities; this is exactly the commutation with mult-by-i that lets R be viewed as a complex-linear operator Rℂ : H →L[ℂ] H, on which the complex continuous functional calculus (CFC.sqrt) applies.

(RS)(iξ)=i(RS)ξ(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,(i \cdot \xi) = i \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,\xi

Proof. By projK, projIK, rvdR_apply, projIK_smul_I, projK_smul_I. \square

Used by rvdR_smul_complex, rvdRC_isSymmetric.

Lemma 771 (clm_eq_of_eqOn_K).  source ↗

Operator equality from equality on 𝒦 (RvD Theorem 3.8 capstone): two continuous -linear operators that agree on the standard subspace 𝒦 agree everywhere. By -linearity they then agree on i𝒦 (q ∈ i𝒦 ⟹ −i·q ∈ 𝒦), hence on the algebraic sum 𝒦 + i𝒦, which is dense (IsCyclic, 𝒦 ⊔ i𝒦 = ⊤); continuity finishes. This lifts the per-vector identity V_t η = Δ^{it} η on 𝒦 (from eq_of_mem_K_of_inner_perp_IK) to the operator identity V_t = Δ^{it} discharging hUniq.

(xS.cl,Ax=Bx)A=B(\forall x\in S.\mathrm{cl}, A\,x = B\,x) \to A = B

Proof. Immediate from the definitions. \square

Used by modUnitary_eq_of_orbit_compare.

Lemma 772 (rvdR_smul_complex).  source ↗

Full ℂ-map_smul for R: R(c·x) = c·(R x) for every c : ℂ. Decompose c = c.re + c.im·i; the real part uses ℝ-linearity, the imaginary part rvdR_smul_I.

(RS)(cx)=c(RS)x(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,(c \cdot x) = c \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,x

Proof. By rvdR_smul_I. \square

Used by rvdRC.

Definition 773 (rvdRC).  source ↗

R = P + Q as a genuine ℂ-linear continuous operator (same underlying map as rvdR S).

RHS  :=  {toFun:=(RS),map_add:=,map_smul:=,cont:=}R\,H\,S \;:=\; \{\mathrm{toFun} :=(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S) , \mathrm{map\_add}^{\prime} :=\cdots , \mathrm{map\_smul}^{\prime} :=\cdots , \mathrm{cont} :=\cdots \}

Used by borelFC_congr_ae, deviceOpC_neg_half_eq, rvdSpecMeasure, devSpecReal, devSpecReal_measurable, devSpecReal_norm_le, deviceOpReal, deviceOpC, and 98 more.

Lemma 774 (rvdRC_apply).  source ↗

(RS)x=(RS)x(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S)\,x = (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,x

Proof. Immediate from the definitions. \square

Used by rvdRC_isPositive, modConj_projIK_modConj, modConj_projK_modConj.

Lemma 775 (rvdRC_isSymmetric).  source ↗

Rℂ is complex-symmetric: ⟪Rℂ x, y⟫_ℂ = ⟪x, Rℂ y⟫_ℂ. Re is rvdR_inner_symm; Im follows from it via the i-twist and ℂ-linearity (rvdR_smul_I).

((RS)).IsSymmetric((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S)).\mathrm{IsSymmetric}

Proof. By rvdR, rvdR_inner_symm, rvdR_smul_I. \square

Used by rvdRC_isPositive, rvdTwoSubRC_isSymmetric, diagInt_specCoord.

Lemma 776 (rvdRC_isPositive).  source ↗

Rℂ is a positive operator in the complex C*-algebra H →L[ℂ] H. Self-adjoint (rvdRC_isSymmetric) with 0 ≤ Re⟪Rℂ x, x⟫ = ⟪R x, x⟫_ℝ (rvdR_inner_self_nonneg). Hence 0 ≤ Rℂ in the Loewner order and the continuous functional calculus square root CFC.sqrt (Rℂ) — the R^{1/2} factor of the Rieffel–Van Daele polar decomposition — is available.

(RS).IsPositive(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S).\mathrm{IsPositive}

Proof. By rvdR, rvdR_inner_self_nonneg, rvdRC_apply, rvdRC_isSymmetric. \square

Used by rvdRC_nonneg.

Lemma 777 (rvdRC_nonneg).  source ↗

0 ≤ Rℂ in the Loewner order (operator nonnegativity), from rvdRC_isPositive.

This is the maximal honest step toward the RvD square root R^{1/2} right now: Rℂ is a genuine positive operator, so R^{1/2} = CFC.sqrt Rℂ is mathematically available — but the Mathlib CFC.sqrt requires StarOrderedRing (H →L[ℂ] H), an instance Mathlib has NOT yet established for operator algebras (it is flagged as future work in InnerProductSpace/Positive.lean: “when we have StarOrderedRing (E →L[𝕜] E)”). So the polar-decomposition factor R^{1/2} is blocked on that single missing instance, not on our construction; rvdRC_isPositive/rvdRC_nonneg is exactly the hypothesis the square root will consume once it lands.

0RS0 \le \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S

Proof. By rvdRC_isPositive. \square

Used by rvdSqrtR_mul_self, rvdRC_isSelfAdjoint, rvdRC_spectrum_mem_Icc, rvdPmQ_commute_rvdT.

Definition 778 (rvdPmQ).  source ↗

RvD P − Q — the self-adjoint operator whose polar decomposition JT = P − Q (RvD Definition 2.1) yields the modular conjugation J and the positive T.

(PQ)HS  :=  PSQS(P-Q)\,H\,S \;:=\; \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projk}{P}\,S - \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-projik}{Q}\,S

Used by rvdPmQ_isSelfAdjoint, rvdPmQ_eq_zero, rvdPmQ_injective, rvdPmQ_smul_I, rvdRC_mul_rvdTwoSubRC_apply, rvdPmQ_commute_A, rvdT_injective, rvdT_norm_eq, and 31 more.

Lemma 779 (rvdPmQ_isSelfAdjoint).  source ↗

P − Q is self-adjoint (its polar decomposition J·T then has J self-adjoint, T ≥ 0).

IsSelfAdjoint((PQ)S)\mathrm{IsSelfAdjoint}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)

Proof. By projK, projIK, projK_isSelfAdjoint, projIK_isSelfAdjoint. \square

Used by rvdT_norm_eq, rvdPmQ_commute_rvdT.

Lemma 780 (rvdPmQ_eq_zero).  source ↗

D = P − Q is injective (kernel-free). Dξ = 0 ⟹ Pξ = Qξ ∈ 𝒦 ∩ i𝒦 = {0} (IsSeparating), so Pξ = Qξ = 0, whence Rξ = Pξ + Qξ = 0 and ξ = 0 (rvdR_eq_zero). Injectivity of D is what makes the modular conjugation J (of D = J·T) a full involution J² = 1 rather than a partial isometry.

((PQ)S)ξ=0ξ=0(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi = 0 \to \xi = 0

Proof. By projK, projIK, rvdR, rvdR_apply, rvdR_eq_zero. \square

Used by rvdPmQ_injective.

Lemma 781 (rvdPmQ_injective).  source ↗

D = P − Q is injective.

Injective((PQ)S)\mathrm{Injective}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)

Proof. By rvdPmQ_eq_zero. \square

Used by rvdT_injective, rvdRC_mul_rvdTwoSubRC_injective.

Lemma 782 (rvdR_le_two).  source ↗

RvD upper bound R ≤ 2 (operator form): 2·1 − R is positive. With rvdR_isPositive (0 ≤ R) this is the complete RvD bound 0 ≤ R ≤ 2 at the operator level — 2 − R is then also positive, so BOTH R^{1/2} and (2 − R)^{1/2} exist by the continuous functional calculus, the two factors of the polar decomposition T = R^{1/2}(2 − R)^{1/2} (RvD Prop 2.2(2)).

(21RS).IsPositive(2 \cdot 1 - \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S).\mathrm{IsPositive}

Proof. By projK, projIK, rvdR_inner_self_le, rvdR_inner_symm. \square

Used by rvdTwoSubRC_isPositive.

Lemma 783 (rvdPmQ_smul_I).  source ↗

D = P − Q is conjugate-linear (anti-ℂ-linear): D(i·ξ) = −i·(D ξ). In contrast to the ℂ-linear R = P + Q (rvdR_smul_I), the difference D anticommutes with mult-by-i — this is exactly the structural reason the modular conjugation J of the polar decomposition J·T = P − Q is antiunitary (conjugate-linear) rather than unitary. Immediate from the conjugation identities projK_smul_I, projIK_smul_I.

((PQ)S)(iξ)=(i((PQ)S)ξ)(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,(i \cdot \xi) = -(i \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi)

Proof. By projK, projIK, projIK_smul_I, projK_smul_I. \square

Used by rvdPmQ_smul_conj.

Definition 784 (rvdTwoSubRC).  source ↗

RvD 2 − R as a ℂ-linear operator. With 0 ≤ R (rvdRC_nonneg) and R ≤ 2 this is the second positive factor (2 − R) whose square root pairs with R^{1/2} in T = R^{1/2}(2 − R)^{1/2}.

(2R)HS  :=  21RS(2-R)\,H\,S \;:=\; 2 \cdot 1 - \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S

Used by cfcCont_sqrtTwoSub_eq, rvdTwoSubRC_apply, rvdTwoSubRC_isSymmetric, rvdTwoSubRC_isPositive, rvdTwoSubRC_nonneg, rvdSqrtTwoSubR, rvdSqrtTwoSubR_nonneg, rvdSqrtTwoSubR_mul_self, and 33 more.

Lemma 785 (rvdTwoSubRC_apply).  source ↗

((2R)S)x=2x(RS)x(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)\,x = 2 \cdot x - (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S)\,x

Proof. By projK, projIK. \square

Used by rvdTwoSubRC_isSymmetric, rvdRC_mul_rvdTwoSubRC_apply, rvdPmQ_commute_rvdT, modConj_projIK_modConj, modConj_projK_modConj, rvdPmQ_mul_rvdRC_rs, rvdRC_E_two_levelSet, modUnitary_commute_rvdPmQ_rs.

Lemma 786 (rvdTwoSubRC_isSymmetric).  source ↗

2 − R is complex-symmetric (1 and Rℂ both are).

(((2R)S)).IsSymmetric((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)).\mathrm{IsSymmetric}

Proof. By rvdR, rvdRC, rvdRC_isSymmetric, rvdTwoSubRC_apply. \square

Used by rvdTwoSubRC_isPositive.

Lemma 787 (rvdTwoSubRC_isPositive).  source ↗

0 ≤ 2 − R (the upper RvD bound R ≤ 2 in operator form). The pointwise reApplyInnerSelf of the ℂ-operator (2:ℂ)•1 − Rℂ is definitionally that of the ℝ-operator (2:ℝ)•1 − R (both are Re⟪(2 • x − R x), x⟫, and (2:ℂ)•x = (2:ℝ)•x), so positivity transfers directly from the already-proven rvdR_le_two.

((2R)S).IsPositive(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S).\mathrm{IsPositive}

Proof. By rvdR, rvdR_le_two, rvdTwoSubRC_isSymmetric. \square

Used by rvdTwoSubRC_nonneg, rvdRC_spectrum_mem_Icc.

Lemma 788 (rvdTwoSubRC_nonneg).  source ↗

0 ≤ 2 − R in the Loewner order.

0(2R)S0 \le \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S

Proof. By rvdTwoSubRC_isPositive. \square

Used by rvdSqrtTwoSubR_mul_self, rvdRC_spectrum_mem_Icc, rvdPmQ_commute_rvdT.

Definition 789 (rvdSqrtR).  source ↗

RvD R^{1/2} — the continuous-functional-calculus square root of R, now available.

R1/2HS  :=  sqrt(RS)R^{1/2}\,H\,S \;:=\; \mathrm{sqrt}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S)

Used by h1_of_stripKMSrvd, gConstancy_of_inputs, oneParticleBW_of_inputs, oneParticleBW_of_stripKMSrvd_density, gConstancy_entire, gFunction_top_edge_real_all, gConstancy_entire_of_bottom, gConstancy_eta_of_bottom, and 32 more.

Definition 790 (rvdSqrtTwoSubR).  source ↗

RvD (2 − R)^{1/2}.

2RHS  :=  sqrt((2R)S)\sqrt{2-R}\,H\,S \;:=\; \mathrm{sqrt}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)

Used by deviceOpC_neg_half_eq, modConj_deviceOpC_neg_half, cfcCont_sqrtTwoSub_eq, rvdSqrtTwoSubR_nonneg, rvdSqrtTwoSubR_mul_self, rvdSqrtR_commute_rvdSqrtTwoSubR, rvdT, rvdT_sq, and 12 more.

Lemma 791 (rvdSqrtR_nonneg).  source ↗

0 ≤ R^{1/2}.

0R1/2S0 \le \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrtr}{R^{1/2}}\,S

Proof. By rvdRC. \square

Used by rvdT_nonneg, modConj_rvdSqrtR_modConj.

Lemma 792 (rvdSqrtTwoSubR_nonneg).  source ↗

0 ≤ (2 − R)^{1/2}.

02RS0 \le \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrttwosubr}{\sqrt{2-R}}\,S

Proof. By rvdTwoSubRC. \square

Used by rvdT_nonneg.

Lemma 793 (rvdSqrtR_mul_self).  source ↗

R^{1/2} · R^{1/2} = R.

R1/2SR1/2S=RS\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrtr}{R^{1/2}}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrtr}{R^{1/2}}\,S = \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S

Proof. By rvdRC_nonneg. \square

Used by rvdT_sq, modConjSqrtR_sq.

Lemma 794 (rvdSqrtTwoSubR_mul_self).  source ↗

(2 − R)^{1/2} · (2 − R)^{1/2} = 2 − R.

2RS2RS=(2R)S\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrttwosubr}{\sqrt{2-R}}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrttwosubr}{\sqrt{2-R}}\,S = \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S

Proof. By rvdTwoSubRC_nonneg. \square

Used by rvdT_sq, rvdSqrtTwoSubR_injective, rvdSqrtR_modConj_of_mem_K.

Lemma 795 (rvdRC_commute_rvdTwoSubRC).  source ↗

R and 2 − R commute (the second is 2·1 − R, an affine function of the first).

Commute(RS)((2R)S)\mathrm{Commute}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S)\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)

Proof. Immediate from the definitions. \square

Used by rvdSqrtR_commute_rvdSqrtTwoSubR, rvdPmQ_commute_rvdT, rvdRC_commute_rvdT, rvdRC_mul_rvdTwoSubRC_isSelfAdjoint, rvdRC_injective.

Lemma 796 (rvdSqrtR_commute_rvdSqrtTwoSubR).  source ↗

The square roots commute: √R = cfcₙ √ R commutes with 2 − R (a function of R), and then with √(2 − R) = cfcₙ √ (2 − R). Both applications use Commute.cfcₙ_nnreal (CFC.sqrt = cfcₙ NNReal.sqrt).

Commute(R1/2S)(2RS)\mathrm{Commute}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrtr}{R^{1/2}}\,S)\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrttwosubr}{\sqrt{2-R}}\,S)

Proof. By rvdRC, rvdTwoSubRC, rvdRC_commute_rvdTwoSubRC. \square

Used by rvdT_sq, rvdT_nonneg, modConj_rvdT_modConj, modConj_fixed_of_sqrtR_mem_K.

Definition 797 (rvdT).  source ↗

RvD T — the positive part of the polar decomposition J·T = P − Q, T = R^{1/2}(2 − R)^{1/2}.

THS  :=  R1/2S2RST\,H\,S \;:=\; \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrtr}{R^{1/2}}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdsqrttwosubr}{\sqrt{2-R}}\,S

Used by rvdT_sq, rvdT_nonneg, rvdT_isSelfAdjoint, rvdT_injective, rvdT_norm_eq, rvdPmQ_commute_rvdT, rvdPmQ_commute_rvdT_apply, rvdT_restrictScalars_denseRange, and 18 more.

Lemma 798 (rvdT_sq).  source ↗

RvD Prop 2.2(2): T² = R(2 − R). Using that R^{1/2} and (2 − R)^{1/2} commute, the product T² = R^{1/2}(2−R)^{1/2}R^{1/2}(2−R)^{1/2} regroups into (R^{1/2})²((2−R)^{1/2})² = R(2−R). With J² = 1 and JT = P − Q, this is (P − Q)² = R(2 − R) — the modular-operator factorization.

TSTS=RS(2R)S\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S = \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S

Proof. By rvdSqrtR, rvdSqrtTwoSubR, rvdSqrtR_mul_self, rvdSqrtTwoSubR_mul_self, rvdSqrtR_commute_rvdSqrtTwoSubR. \square

Used by rvdT_injective, rvdT_norm_eq, rvdPmQ_commute_rvdT.

Lemma 799 (rvdT_nonneg).  source ↗

T = R^{1/2}(2−R)^{1/2} is positive — a product of two commuting positive operators.

0TS0 \le \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S

Proof. By rvdSqrtR, rvdSqrtTwoSubR, rvdSqrtR_nonneg, rvdSqrtTwoSubR_nonneg, rvdSqrtR_commute_rvdSqrtTwoSubR. \square

Used by rvdT_isSelfAdjoint, rvdPmQ_commute_rvdT.

Lemma 800 (rvdT_isSelfAdjoint).  source ↗

T is self-adjoint (it is positive).

IsSelfAdjoint(TS)\mathrm{IsSelfAdjoint}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S)

Proof. By rvdT_nonneg. \square

Used by rvdT_norm_eq, rvdT_restrictScalars_denseRange, rvdT_real_inner_symm.

Lemma 801 (rvdRC_mul_rvdTwoSubRC_apply).  source ↗

T² = D² as maps: (R(2−R)) ξ = (P − Q)((P − Q) ξ). Both sides reduce to P ξ + Q ξ − P(Q ξ) − Q(P ξ) by idempotency of P, Q (R² = R + (PQ+QP), so R(2−R) = 2R − R² = R − (PQ+QP) = (P−Q)²). This is what transfers ‖T ξ‖ = ‖D ξ‖ (the modular conjugation is an isometry from T to D).

(RS(2R)S)ξ=((PQ)S)(((PQ)S)ξ)(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)\,\xi = (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi)

Proof. By projK, projIK, rvdR, projK_idem, projIK_idem, rvdTwoSubRC_apply. \square

Used by rvdPmQ_commute_A, rvdT_injective, rvdT_norm_eq, rvdRC_mul_rvdTwoSubRC_injective.

Lemma 802 (rvdPmQ_commute_A).  source ↗

D commutes with A = R(2−R) = T² (the inductive base for D·T = T·D). Trivial because A = D² as maps (rvdRC_mul_rvdTwoSubRC_apply): D·D² = D³ = D²·D. The full D·√A = √A·D (the antilinear modular-conjugation commutation, whence J² = 1) follows from this base by the closed-commutant argument — {Y | D∘Y = Y∘D} is a closed real *-subalgebra ⊇ elemental ℝ A ∋ √A.

((PQ)S)((RS(2R)S)ξ)=(RS(2R)S)(((PQ)S)ξ)(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)\,\xi) = (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdrc}{R}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdtwosubrc}{(2-R)}\,S)\,((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi)

Proof. By rvdRC_mul_rvdTwoSubRC_apply. \square

Used by rvdPmQ_commute_rvdT, modUnitary_commute_rvdPmQ_rs.

Lemma 803 (rvdT_injective).  source ↗

T = R^{1/2}(2−R)^{1/2} is injective. T² = R(2−R) = D² (rvdT_sq, rvdRC_mul_rvdTwoSubRC_apply) is injective because D = P−Q is (rvdPmQ_injective), and T injective follows. T injective ⟹ range T dense ((range T)‾ = (ker T)ᗮ = H), which is what makes the modular conjugation J : T ξ ↦ D ξ extend to all of H.

Injective(TS)\mathrm{Injective}\,(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S)

Proof. By rvdRC, rvdPmQ, rvdPmQ_injective, rvdTwoSubRC, rvdT_sq, rvdRC_mul_rvdTwoSubRC_apply. \square

Used by rvdT_restrictScalars_denseRange, modConj_fixed_of_sqrtR_mem_K.

Lemma 804 (rvdT_norm_eq).  source ↗

The modular-conjugation isometry: ‖T ξ‖ = ‖D ξ‖ (RvD polar decomposition D = J·T). D = P − Q is conjugate-linear and T = R^{1/2}(2−R)^{1/2} is its positive modulus |D|; the map J : T ξ ↦ D ξ is therefore a well-defined antiunitary (the modular conjugation). Proved from T² = D² (rvdRC_mul_rvdTwoSubRC_apply via rvdT_sq) and self-adjointness of both T and D.

(TS)ξ=((PQ)S)ξ\|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdt}{T}\,S)\,\xi\| = \|(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi\|

Proof. By rvdRC, rvdPmQ_isSelfAdjoint, rvdTwoSubRC, rvdT_sq, rvdT_isSelfAdjoint, rvdRC_mul_rvdTwoSubRC_apply. \square

Used by modConj_rvdT, modConj_norm.

Lemma 805 (rvdPmQ_mul_rvdR).  source ↗

RvD intertwiner D·R = (2−R)·D.

(PQ)SRS=(21RS)(PQ)S\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S = (2 \cdot 1 - \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S) \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S

Proof. By projK, projIK, projK_idem, projIK_idem. \square

Used by rvdPmQ_anticommute_rvdR_sub_one, rvdPmQ_mul_rvdRC_rs.

Lemma 806 (rvdPmQ_anticommute_rvdR_sub_one).  source ↗

D ANTICOMMUTES with R − 1: D·(R−1) = −(R−1)·D. Because D·R = (2−R)·D (rvdPmQ_mul_rvdR), so D·(R−1) = (2−R)·D − D = (1−R)·D = −(R−1)·D. This is the engine for the modular covariance [U_t, D] = 0: D antilinear + D·(R−1)=−(R−1)·D makes D COMMUTE with i·(R−1), and U_t = u_t(R) is (a Borel function) of i·(R−1) with conj(u_t(2−r)) = u_t(r).

(PQ)S(RS1)=((RS1)(PQ)S)\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S - 1) = -((\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdr}{R}\,S - 1) \cdot \href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)

Proof. By rvdPmQ_mul_rvdR. \square

Used by rvdPmQ_rvdRC.

Lemma 807 (rvdPmQ_smul_conj).  source ↗

D is conjugate-(ℂ-)linear: D(c•ξ) = conj(c)·Dξ for every c : ℂ. From ℝ-linearity plus the i-case rvdPmQ_smul_I (D(i•ξ)=−i•Dξ), expanding c = c.re + c.im·i.

((PQ)S)(cξ)=(starRingEndC)c((PQ)S)ξ(\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,(c \cdot \xi) = (\mathrm{starRingEnd}\,\mathbb{C})\,c \cdot (\href{/browser/qiqth-standardsubspacemodular#d-qiqth-standardsubspacemodular-rvdpmq}{(P-Q)}\,S)\,\xi

Proof. By rvdPmQ_smul_I. \square

Used by cfcΩ_intertwine.


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