Functional layer (PLFA/EDE/EVI/JKO bridge skeleton)
This module introduces a lightweight functional container and constants
to connect the FG8 framework with the existing analysis layer. The goal
is to keep the API proof-light while exposing the key
quantities and inequalities used later: the base entropy Ent
, the
Mellin-side term Dsigmam
, a coupling parameter gamma
, and the Doob
corrected parameter lambdaBE = λ - 2 ε
. We also provide a parameterized
lower-bound predicate for the effective contraction rate.
Core functional container.
Instances For
Build a FrourioFunctional
from an entropy Ent
, a K-transform K
,
and a parameter gamma
, using the DsigmamFromK
interface with a supplied
sup-norm proxy Ssup
.
Equations
- Frourio.FrourioFunctional.ofK Ent K gamma Ssup = { Ent := Ent, Dsigmam := Frourio.DsigmamFromK K Ssup, gamma := gamma }
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Narrow-continuity surrogate:
we require a uniform lower bound for Dsigmam
(coercivity proxy).
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Geodesic-affinity surrogate:
we assume nonnegativity of the coupling parameter gamma
.
This encodes that the extra term does not invert convexity trends.
Equations
- Frourio.K4m A = (0 ≤ A.gamma)
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If the K-transform has a uniform lower bound at s = 0
by -C0
and the
scale Ssup
is nonnegative, then the derived Dσm(x) = Ssup · K.map x 0
is
bounded below by -(Ssup · C0)
. Hence the K1′
surrogate holds for the
functional built from K
.
Numeric lower bound for F = Ent + γ · Dσm
built from a KTransform
with
uniform kernel lower bound at s = 0
. If γ ≥ 0
and Ssup ≥ 0
, then
F(x) ≥ Ent(x) - γ · (Ssup · C0).
This inequality is used as a coercivity proxy downstream.
If K1prime
holds for the functional built from K
, and Ent
has a uniform
lower bound, then the combined functional F
is Coercive.
If the functional built from K
satisfies K1prime
, then it is LowerSemicontinuous
(in the surrogate sense).
The functional built from K
satisfies the Proper predicate (surrogate).
The functional built from K
satisfies HalfConvex (surrogate).
The functional built from K
satisfies StrongUpperBound (surrogate).
If gamma ≥ 0, then K4^m holds for the functional built from K.
The functional built from K
satisfies JKOStable (surrogate).
For any initial point, there exists a curve (the constant curve) along which F is non-increasing.
JKO stability for general FrourioFunctional. This provides the JKO property for any FrourioFunctional, showing that from any initial point, there exists a (constant) curve along which F is non-increasing.
JKO property with explicit curve construction. Given an initial point, construct a JKO curve (constant curve in the surrogate case).
Equations
- Frourio.constructJKOCurve ρ0 x✝ = ρ0
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The constructed JKO curve satisfies the JKO property.
K4^m is preserved under scaling of gamma by a nonnegative factor.
If both K1′ and K4^m hold, the functional has controlled behavior.
Budget constants entering the effective-rate bound.
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Lower bound predicate for the effective contraction rate λ_eff
.
Parameters Ssup
and XiNorm
act as proxies for ‖S_m‖_∞
and ‖Ξ_m‖
.
λ_eff ≥ (λ - 2 ε) - γ · (cStar · Ssup^2 + cD · XiNorm)
Equations
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Theoremized form: wrap a provided inequality as the lambdaEffLowerBound
fact.
Monotonicity in lamEff
: if a witness lamEff
satisfies the inequality,
then any lamEff' ≥ lamEff
also satisfies it.
Equations
- Frourio.MPointZeroOrderBound Ssup XiNorm = (0 ≤ Ssup ∧ 0 ≤ XiNorm)
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Parametric StrongUpperBound for Dσm's Zero-Order Contribution #
This section provides the parametric strong upper bound for the zero-order contribution of Dσm, controlled by the budget constants.
Upper bound for Dσm based on kernel evaluation at s=0.
Zero-order contribution bound for Dσm in the functional F = Ent + γ·Dσm.
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The functional F = Ent + γ·Dσm satisfies parametric StrongUpperBound when Ent is bounded above and Dσm has zero-order bound.
Budget-aware StrongUpperBound: Connect budget constants to the upper bound.
Integration: StrongUpperBound from kernel bound and budget parameters.
Variant using the concrete Doob assumptions pack. This theorem connects
DoobAssumptions
to the λ_eff lower bound generation. The Doob transform
provides λ_BE = λ - 2ε, and the m-point terms provide additional corrections.
API: Direct connection from DoobAssumptions to the effective rate formula. Given DoobAssumptions with parameter ε, we get λ_eff ≥ (λ - 2ε) - γ·(m-point terms).
Constructive variant using DoobAssumptions
: produce an explicit
lamEff
witnessing the lower bound, given m-point zero-order bounds and
budget nonnegativity. The Doob CD-shift is tracked via DoobAssumptions
but not quantitatively used at this phase.
Main Lambda Effective Lower Bound with Doob Pack #
This section provides the main theorem for deriving the effective lambda lower bound from the Doob pack (λ - 2ε) and m-point 0-order term budget (c_*, c_D, Ssup, XiNorm).
Main theorem: Derive λ_eff lower bound from Doob pack and m-point budget. Given a Doob transform with parameter ε and m-point zero-order bounds, we obtain: λ_eff ≥ (λ - 2ε) - γ·(c_* · Ssup² + c_D · XiNorm).
Special case for commutative designs: When c_* = 0, the formula simplifies. In commutative designs, the star term vanishes, giving: λ_eff ≥ (λ - 2ε) - γ·(c_D · XiNorm).
Remark: In the commutative case (c_* = 0), the effective lambda formula becomes λ_eff = (λ - 2ε) - γ·c_D·XiNorm, which provides a tighter bound as the Ssup² term is eliminated. This is particularly relevant for:
- Symmetric diffusion operators
- Gradient flows on Riemannian manifolds with parallel transport
- Heat flow on groups with bi-invariant metrics
Constructor for effective lambda with explicit Doob pack and m-point budget. This provides a convenient API for downstream usage.
Equations
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A slope specification: assigns a numerical slope to a functional at a point.
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Default (dummy) slope specification used at this phase: always 0.
Equations
- Frourio.zeroSlopeSpec X = { slope := fun (x : X → ℝ) (x : X) => 0 }
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Implemented slope specification using the descending slope.
Equations
- Frourio.descendingSlopeSpec X = { slope := fun (F : X → ℝ) (x : X) => Frourio.descendingSlope F x }
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Legacy slope alias (kept for existing code); uses the zero slope.
Equations
- Frourio.slope G x = (Frourio.zeroSlopeSpec X).slope G x
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Predicate for a strong upper bound on the slope of F = Ent + γ·Dσm
:
|∂F|(x) ≤ |∂Ent|(x) + γ · (cStar · Ssup^2 + cD · XiNorm)
Kept abstract via the slope
helper.
Equations
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Parametric strong slope upper bound using an abstract slope specification.
Equations
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Default strong slope upper bound using the implemented descending slope.
Equations
- Frourio.StrongSlopeUpperBound A budget Ssup XiNorm = Frourio.StrongSlopeUpperBound_with (Frourio.descendingSlopeSpec X) A budget Ssup XiNorm
Instances For
The legacy predicate StrongSlopeUpperBound_pred
is the StrongSlopeUpperBound_with
for the default zero slope.
Theoremized strong slope upper bound (wrapper from the predicate).
Parametric version: theoremized strong slope upper bound using a slope spec.
Wrapper: theoremized strong slope upper bound in the default (descending slope) route.
A slope upper bound using the zero slope and nonnegativity.
HalfConvex Flag for λ_BE-Geodesic Semiconvexity #
This section provides the connection between Ent's λ_BE-geodesic semiconvexity and the HalfConvex flag required by the PLFA framework.
Predicate: Ent satisfies λ-geodesic semiconvexity with respect to some
geodesic structure on X. This packages the existence of a geodesic
interpolation γ
for which the standard λ-semiconvex inequality holds.
Equations
- Frourio.EntGeodesicSemiconvex Ent lambda = ∃ (G : Frourio.GeodesicStructure X), Frourio.GeodesicSemiconvex G Ent lambda
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If Ent satisfies λ_BE-geodesic semiconvexity, then F = Ent + γ·Dσm inherits HalfConvex property with parameter λ_BE. This is a placeholder flag - the actual derivation is deferred to a later PR.
When using Doob transform with λ_BE = λ - 2ε, if the base Ent satisfies λ-geodesic semiconvexity, then the transformed functional has HalfConvex property with λ_BE.
Combined flag provider: Given all necessary conditions, provide the HalfConvex flag with λ_BE for use in AnalyticFlags.
Equations
- ⋯ = ⋯
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API: Extract HalfConvex flag from DoobQuantitative pack. This provides the flag needed for AnalyticFlagsReal.
Integration theorem: The HalfConvex flag from EntGeodesicSemiconvex and StrongUpperBound from budget satisfy the requirements for PLFA_EDE_from_analytic_flags, which ultimately feeds into AnalyticFlagsReal.
Proper Property for AnalyticFlagsReal #
This section provides the proper property in the real sense (not surrogate) for F=Ent+γDσm, as required by AnalyticFlagsReal.
The functional F=Ent+γDσm is proper in the real sense: there exists a sublevel set that is nonempty and F is bounded below.
Alternative: proper property using uniform bounds from K1'.
Comparison: The surrogate Proper
is weaker than the real proper
.
Helper: Convert real proper to surrogate proper for the functional.
Lower Semicontinuity for AnalyticFlagsReal #
This section provides the lower semicontinuous property in Mathlib's sense for F=Ent+γDσm, as required by AnalyticFlagsReal.
Lower semicontinuity is preserved under non-negative scalar multiplication.
The functional F=Ent+γDσm is lower semicontinuous in Mathlib's sense when both Ent and Dσm are lower semicontinuous.
Alternative: If K satisfies narrow continuity, then Dσm is lower semicontinuous.
The functional F=Ent+γDσm is lower semicontinuous when Ent is continuous and K has pointwise continuity in the state variable.
Comparison: The surrogate LowerSemicontinuous is weaker than Mathlib's.
Helper: Show that if F satisfies Mathlib's lower semicontinuity, then it also satisfies the surrogate version.
Coercivity for AnalyticFlagsReal #
This section provides the coercive property in the real mathematical sense for F=Ent+γDσm, as required by AnalyticFlagsReal.
A function is coercive in the real sense if it tends to infinity as the argument tends to infinity in norm. This is the standard definition used in optimization and PDE theory.
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Alternative characterization: f(x) → ∞ as ‖x‖ → ∞
Equations
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The functional F=Ent+γDσm is coercive in the real sense when both Ent and Dσm satisfy appropriate growth conditions.
Helper: The surrogate coercive property is weaker than the real one.
Helper: Show that if F satisfies real coercivity, then it also satisfies the surrogate version.
Geodesic Structure for Real Analytic Flags #
This section provides the geodesic structure and semiconvexity properties needed for AnalyticFlagsReal.
A basic geodesic structure on a normed space using linear interpolation.
Equations
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Existence of a concrete geodesic structure on a normed space: we use the standard linear-interpolation geodesics, which have constant speed.
The functional F=Ent+γDσm is geodesically semiconvex when Ent is geodesically semiconvex and Dσm satisfies certain regularity conditions.
Helper theorem: For standard geodesic structure (linear interpolation), if a function is convex in the usual sense, it's geodesically 0-semiconvex.
Semiconvexity for Real Analytic Flags #
This section provides semiconvexity properties needed for AnalyticFlagsReal.
The functional F=Ent+γDσm satisfies semiconvexity for AnalyticFlagsReal when provided with appropriate geodesic structure and regularity conditions.
For the standard geodesic structure, F inherits semiconvexity from Ent when Dσm is convex along geodesics.
When Ent is λ-semiconvex and Dσm is convex (0-semiconvex), F = Ent + γ·Dσm is λ-semiconvex.
Compact Sublevels for Real Analytic Flags #
This section provides compact sublevel set properties needed for AnalyticFlagsReal.
A functional has compact sublevels if all sublevel sets are compact.
Instances For
The functional F=Ent+γDσm has compact sublevels when both Ent and Dσm have appropriate growth conditions and the space has suitable compactness properties.
Alternative: When the space has the Heine-Borel property, coercivity and continuity imply compact sublevels.
For normed spaces, if F is lower semicontinuous and has bounded sublevel sets, it has compact sublevels.
Slope Bounds for AnalyticFlagsReal #
This section provides bounds on the descending slope needed for AnalyticFlagsReal.
Helper Lemmas for Slope Bounds #
These lemmas establish the subadditivity properties needed for slope bounds.
Helper lemmas for EReal-based proofs #
Subadditivity of descending slope for sums.
Scaling property of descending slope.
Lipschitz functions have bounded descending slope.
The descending slope of F=Ent+γDσm is bounded when Ent has bounded slope.
When the entropy is Lipschitz, we get an explicit slope bound.
Complete AnalyticFlags Assembly #
This section shows that F=Ent+γDσm can provide all necessary flags for AnalyticFlags, completing the goal.
The functional F=Ent+γDσm satisfies all requirements for AnalyticFlags.
Alternative constructor using DoobQuantitative for λ_BE.
Summary: F=Ent+γDσm can supply AnalyticFlags.
Bridge Applications: PLFA/EDE and EDE/EVI #
This section applies the bridge theorems from PLFACore0 and PLFACore2/3 to our functional F.
Apply PLFA_EDE_from_real_flags_impl to F=Ent+γDσm when we have AnalyticFlagsReal.
Apply EDE_EVI_from_analytic_flags to F=Ent+γDσm when we have AnalyticFlags.
Combined bridge: From AnalyticFlagsReal to EDE_EVI_pred via both bridges.
Full Equivalence Package: PLFA/EDE/EVI/JKO #
This section establishes the full equivalence package for the Frourio functional F using the real analytic flags route.
Full equivalence package for F=Ent+γDσm using real analytic flags. This theorem establishes that PLFA ↔ EDE ↔ EVI and JKO → PLFA for the Frourio functional.
EVI Form with FG Interoperability #
This section provides predicates that connect the Frourio functional F to EVIProblem structures with FG (Frourio Geometry) interoperability.
Create an EVIProblem from the Frourio functional F=Ent+γDσm.
Equations
- Frourio.ofK_to_EVIProblem Ent K gamma Ssup lamEff = { E := (Frourio.FrourioFunctional.ofK Ent K gamma Ssup).F, lam := lamEff }
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Predicate: ρ is an EVI solution for the Frourio functional.
Equations
- Frourio.ofK_IsEVISolution Ent K gamma Ssup lamEff ρ = Frourio.IsEVISolution (Frourio.ofK_to_EVIProblem Ent K gamma Ssup lamEff) ρ
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Bridge from FGData to Frourio functional EVI problem. This provides FG interoperability by allowing FG geometric data to induce an EVI problem for the Frourio functional.
Equations
- Frourio.ofK_from_FGData Ent K gamma Ssup FG = { E := (Frourio.FrourioFunctional.ofK Ent K gamma Ssup).F, lam := FG.lam }
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Predicate: ρ is an EVI solution for F with parameters from FGData.
Equations
- Frourio.ofK_fg_IsEVISolution Ent K gamma Ssup FG ρ = Frourio.IsEVISolution (Frourio.ofK_from_FGData Ent K gamma Ssup FG) ρ
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Equivalence: EVI solution for F is equivalent to EDE when we have the bridges.
Contraction property for two EVI solutions of the Frourio functional.
Equations
- Frourio.ofK_evi_contraction Ent K gamma Ssup lamEff u v hu hv = Frourio.evi_contraction (Frourio.ofK_to_EVIProblem Ent K gamma Ssup lamEff) u v hu hv
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MinimizingMovement Interoperability #
This section provides lemmas connecting the MinimizingMovement scheme (JKO scheme) with the Frourio functional F.
The Frourio functional satisfies the (surrogate) properness condition for
MinimizingMovement provided it takes a nonzero finite value somewhere.
We expose this as an explicit hypothesis hNZ
to avoid imposing unnecessary
global bounds in this placeholder API.
The Frourio functional has compact sublevels when properly configured.
Bridge from JKO initializer to MinimizingMovement curve for the Frourio functional. Uses classical choice to construct the sequence of minimizers.
Connection between MinimizingMovement steps and PLFA curves in the limit. This shows that discrete MM curves converge to PLFA solutions as τ → 0. TODO: This requires standard MM convergence theory with compactness and Γ-convergence.
MinimizingMovement step preserves the energy decrease property for F.
Two-EVI with Force for Frourio Functional #
This section provides aliases for TwoEVIWithForce and distance synchronization corollaries specialized for the Frourio functional F.
Two-EVI with force for the Frourio functional F.
Equations
- Frourio.ofK_TwoEVIWithForce Ent K gamma Ssup lamEff u v = Frourio.TwoEVIWithForce (Frourio.ofK_to_EVIProblem Ent K gamma Ssup lamEff) u v
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Distance synchronization from Two-EVI with force for F.
Concrete distance synchronization for F without external bridge hypothesis.
Closed form: if Grönwall holds for all η, then Two-EVI with force for F yields distance synchronization.
Tensorization #
This section provides thin wrappers for expressing existing minimization rules in terms of EVIProblem products. The tensorization allows us to handle multiple EVIProblems simultaneously and derive properties of their products.
IMPORTANT: The default product metric in Lean/Mathlib is the l∞ (max) metric, not the l2 (Euclidean) metric. The theorems below that assume additive decomposition of squared distances would require an explicit l2 product metric instance.
Product of two EVIProblems. The energy is the sum of component energies, and the parameter is the minimum of component parameters.
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Notation for EVIProblem product
Equations
- Frourio.«term_⊗_» = Lean.ParserDescr.trailingNode `Frourio.«term_⊗_» 70 70 (Lean.ParserDescr.binary `andthen (Lean.ParserDescr.symbol " ⊗ ") (Lean.ParserDescr.cat `term 71))
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If both component curves are EVI solutions, their product is an EVI solution for the product problem (with the minimum lambda). NOTE: This requires an l2-type product metric where d²((x,y),(x',y')) = d²(x,x') + d²(y,y'). The default Lean product metric is l∞ (max), so this theorem needs a custom metric instance.
Projection: EVI solution for product implies EVI for first component when lambda matches. NOTE: This works with the default l∞ metric, but the relationship between product and component EVI is more complex than with l2 metric.
Projection: EVI solution for product implies EVI for second component when lambda matches.
Triple product of EVIProblems
Equations
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Minimization rule for product: if each component has a minimizer, the product has a minimizer (assuming proper/coercive energies and lower semicontinuity).
Energy decrease for product: if both components decrease energy, the product decreases energy.
Frourio functional as an EVIProblem. This wraps F = Ent + γ·Dσm as a single EVIProblem with effective lambda. NOTE: Despite the name, this is not actually a product structure.
Equations
- Frourio.ofK_as_EVIProblem Ent K gamma Ssup lamEff = { E := (Frourio.FrourioFunctional.ofK Ent K gamma Ssup).F, lam := lamEff }
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Decomposed representation: separate EVIProblems for Ent and Dσm components. This returns a pair of problems, not a product EVIProblem on X×X.
Equations
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When F satisfies EVI with λ_eff, it satisfies the EVIProblem formulation.
N-fold product for homogeneous systems
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Homogeneous product: N identical EVI solutions yield product solution. NOTE: This assumes an l2-type metric on Fin n → X where distances decompose additively. The default product metric is l∞, which requires different treatment.
Synchronized product: when all components evolve with the same curve. NOTE: This requires the same l2-type metric assumption as isEVISolution_power_l2.
Multi-scale Exponential Laws #
This section provides wrappers for λ_eff under multi-scale transformations following the scaling laws from FG (Frourio Geometry) framework as described.
The effective lambda under scaling transformation is: λ_eff = Λ^((κ - 2α)k) · λ where:
- Λ > 1 is the metal ratio (scaling factor)
- k ∈ ℤ is the scale level
- κ > 0 is the generator homogeneity exponent
- α ≥ 0 is the metric scaling exponent (0 for isometry, >0 for similarity)
Compute the effective lambda at scale level k under scaling transformation. Formula: λ_eff = Λ^((κ - 2α)k) · λ
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The exponential scaling factor for lambda
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When κ = 2α (critical balance), the effective lambda is scale-invariant
Special case: isometric scaling (α = 0)
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- One or more equations did not get rendered due to their size.
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For isometric scaling, λ_eff = Λ^(κk) · λ
Special case: Euclidean similarity (α = 1)
Equations
- Frourio.euclideanScalingParams Lambda kappa hLambda hkappa = { Lambda := Lambda, kappa := kappa, alpha := 1, hLambda := hLambda, hkappa := hkappa, halpha := ⋯ }
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For Euclidean similarity, λ_eff = Λ^((κ-2)k) · λ
Scaling parameters with golden ratio
Equations
- One or more equations did not get rendered due to their size.
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Multi-scale EVI predicate for Frourio functional under scaling
Equations
- Frourio.ofK_IsEVISolution_scaled Ent K gamma Ssup lam params k u = Frourio.ofK_IsEVISolution Ent K gamma Ssup (Frourio.lambdaEffScaled params lam k) u
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Existence of scaled solution with adjusted lambda