Pointwise energy density for maps from the standard complex line #
This file records pointwise energy-density bookkeeping. For a compatible pair (ω, J), the
associated metric is g(v, w) = ω(v, J w). If a real-linear map F : ℝ × ℝ → V is complex-linear,
then the standard energy density g(F ∂s, F ∂s) + g(F ∂t, F ∂t) is twice the symplectic area
density ω(F ∂s, F ∂t).
Under a taming symplectic form the density is moreover nondegenerate: it is nonnegative for every
real-linear map, vanishes exactly for the zero map, and is positive otherwise. The
Frechet-derivative versions specialize this to pointwise and within-set constant-structure
J-holomorphic maps.
For an arbitrary real-linear map the density obeys the Wirtinger inequality
2 ω(F ∂s, F ∂t) ≤ g(F ∂s, F ∂s) + g(F ∂t, F ∂t), the pointwise form of E(u) ≥ ∫ u^*ω: the
difference is the Cauchy--Riemann defect square g(F ∂s + J (F ∂t), F ∂s + J (F ∂t)), which
vanishes exactly when F is complex linear, so the inequality is an equality precisely for
constant-structure J-holomorphic maps. This is the linear-algebra content behind
"constant-structure J-holomorphic curves minimize
energy in their homology class".
The statements here are pointwise linear algebra and Frechet-derivative calculus. They are
integrated over a measure space in
TauCeti.Geometry.Symplectic.JHolomorphic.Energy.Integral.
Main declarations #
TauCeti.SymplecticForm.stdComplexLineEnergyDensity: the metric energy density of a real-linear map from the standard complex line.TauCeti.IsComplexLinearMap.stdComplexLineEnergyDensity_eq_two_mul_symplecticForm: for a complex-linear map, energy density is twice symplectic area density.IsConstStructureJHolomorphicAt.fderiv_stdComplexLineEnergyDensity_eq_two_mul_symplecticForm: the corresponding Frechet-derivative statement for a pointwise constant-structureJ-holomorphic map.TauCeti.SymplecticForm.stdComplexLineEnergyDensity_posandTauCeti.SymplecticForm.stdComplexLineEnergyDensity_eq_zero_iff: nondegeneracy of the density under tameness, withTauCeti.IsConstStructureJHolomorphicAt.fderiv_stdComplexLineEnergyDensity_eq_zero_iffandIsConstStructureJHolomorphicWithinAt.fderivWithin_stdComplexLineEnergyDensity_eq_zero_iffthe Frechet-derivative versions.TauCeti.SymplecticForm.prod_stdComplexLineEnergyDensity: product-target energy density is the sum of the factor energy densities.TauCeti.SymplecticForm.stdComplexLineEnergyDensity_sub_two_mul_symplecticForm: the Wirtinger identityenergyDensity F - 2 ω(F ∂s, F ∂t) = g(F ∂s + J (F ∂t), F ∂s + J (F ∂t)).TauCeti.SymplecticForm.two_mul_symplecticForm_le_stdComplexLineEnergyDensity: the Wirtinger inequality2 ω(F ∂s, F ∂t) ≤ energyDensity Ffor a compatible pair, with the Frechet-derivative corollariesTauCeti.SymplecticForm.two_mul_symplecticForm_fderiv_le_stdComplexLineEnergyDensityandTauCeti.SymplecticForm.two_mul_symplecticForm_fderivWithin_le_stdComplexLineEnergyDensity.TauCeti.SymplecticForm.stdComplexLineEnergyDensity_eq_two_mul_symplecticForm_iff: equality holds exactly for complex-linear (constant-structureJ-holomorphic) maps.
The convention follows McDuff--Salamon, J-holomorphic Curves and Symplectic Topology,
Section 2.1: for a compatible pair, g(·, ·) = ω(·, J ·) and du(∂t) = J du(∂s).
The pointwise metric energy density of a real-linear map from the standard complex line.
For a compatible pair (ω, J), this is
g(F ∂s, F ∂s) + g(F ∂t, F ∂t), where g(v,w) = ω(v, J w).
Instances For
The standard complex-line energy density is the sum of the associated bilinear form evaluated on the images of the standard real and imaginary basis vectors.
The zero real-linear map has zero standard complex-line energy density. No hypothesis
relating ω and J is needed, unlike in
TauCeti.SymplecticForm.stdComplexLineEnergyDensity_eq_zero_iff.
The standard pointwise energy density of any real-linear map is nonnegative under tameness.
Under tameness, the standard pointwise energy density of a nonzero real-linear map from the standard complex line is positive.
Under tameness, standard pointwise energy density vanishes exactly for the zero real-linear map from the standard complex line.
Under tameness, the standard pointwise energy density is positive exactly for nonzero real-linear maps from the standard complex line.
Under tameness, standard pointwise energy density of a continuous linear map vanishes exactly when the continuous linear map is zero.
Under tameness, the standard pointwise energy density of a continuous linear map is positive exactly when the continuous linear map is nonzero.
The standard-line energy density of a real-linear map into a direct-sum target is the sum of the two factor energy densities of its coordinate projections.
For a complex-linear map out of the standard complex line, the associated-bilinear-form diagonal of the imaginary-coordinate image equals that of the real-coordinate image.
For a complex-linear map out of the standard complex line, the real-coordinate associated-bilinear-form diagonal is the symplectic area density of the ordered coordinate pair.
For a complex-linear map out of the standard complex line, the standard pointwise energy density is twice the symplectic area density.
For a pointwise constant-structure J-holomorphic map from the standard complex line, the
associated-bilinear-form diagonal of the ∂t derivative equals that of the ∂s derivative.
For a pointwise constant-structure J-holomorphic map from the standard complex line, the ∂s
associated-bilinear-form diagonal is the symplectic area density ω(∂s u, ∂t u).
For a pointwise constant-structure J-holomorphic map from the standard complex line, the
derivative's
standard energy density is twice its symplectic area density.
The derivative's standard pointwise energy density is nonnegative under tameness.
Under tameness, the derivative standard energy density of a map from the standard complex line vanishes exactly when its Frechet derivative is zero.
Under tameness, the derivative standard energy density of a map from the standard complex line is positive exactly when its Frechet derivative is nonzero.
Under tameness, a map with nonzero Frechet derivative has positive standard derivative energy density.
For a within-set constant-structure J-holomorphic map from the standard complex line, the
associated-bilinear-form diagonal of the ∂t derivative equals that of the ∂s derivative,
provided derivatives within the set are unique.
For a within-set constant-structure J-holomorphic map from the standard complex line, the ∂s
associated-bilinear-form diagonal is the symplectic area density ω(∂s u, ∂t u),
provided derivatives within the set are unique.
For a within-set constant-structure J-holomorphic map from the standard complex line, the
derivative's
standard energy density is twice its symplectic area density, provided derivatives within the
set are unique.
The within-set derivative's standard pointwise energy density is nonnegative under tameness.
Under tameness, the within-set derivative standard energy density of a map from the standard complex line vanishes exactly when its Frechet derivative within the set is zero.
Under tameness, the within-set derivative standard energy density is positive exactly when the Frechet derivative within the set is nonzero.
Under tameness, a map with nonzero Frechet derivative within a set has positive standard derivative energy density.
The Wirtinger identity out of the standard complex line: the standard energy density minus
twice the symplectic area density is the Cauchy--Riemann defect square
g(F ∂s + J (F ∂t), F ∂s + J (F ∂t)). Needs only J-invariance of ω.
Wirtinger inequality. For a compatible pair (ω, J) and any real-linear map out of the
standard complex line, twice the symplectic area density of the ordered coordinate pair is at
most the standard energy density: the local form of E(u) ≥ ∫ u^*ω.
The Wirtinger inequality is an equality exactly when the map is complex linear, that is,
constant-structure J-holomorphic out of the standard complex line: the energy density then equals
twice the
symplectic area density.
The Wirtinger inequality for the Frechet derivative of any map from the standard complex line: twice the symplectic area density of the derivative's coordinate pair is at most its standard energy density.
The Wirtinger inequality for the within-set Frechet derivative of any map from the standard complex line.