Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
Sigma-Algebra of Events Prior to a Stopping Time
definitiondef:stopping-time-sigma-algebra-2026aProbabilityLet be a probability space, let be a real number, let be a filtration on with time index restricted to , and let be a stopping time of . The…Stopping Time of a Filtration on a Compact Time Interval
definitiondef:stopping-time-2026aProbabilityLet be a probability space, let be a real number, and let be a filtration on with time index restricted to . A stopping time of is a function…Restricted First Moments and Tail Bounds for the Martingale Part of the Empirical State Measure
lemmalem:n-agent-martingale-restricted-moments-2026aProbabilityAdopt the setting of the moment bounds for the aggregate compensated counters with agents, states, observation channels, and control dimension : a transition-rate family with control set , a nonempty subset of Euclidean space…Pointwise-in-Time Tracking of the Mean-Field Flow and Cost along the Realized Control of the Controlled N-Agent Dynamics
lemmalem:n-agent-pathwise-tracking-2026aAnalysisProbabilityAdopt the setting, hypotheses, and notation of the comparison lemma for the -agent system and the mean-field flow: the affine-controlled transition-rate family on states with control set and its transition-rate family…First-Order Expansion of the Mean-Field Cost about a Stationary Mean-Field Triple and Its Quadratic Lower Bound
lemmalem:mean-field-cost-first-order-identity-2026aAnalysisMultivariable CalculusLet , , , with rate bound , with derivative bound , , , with second-derivative bound (the open set of the cost extension, written in that definition, is written here),…Quadratic Growth of the Mean-Field Hamiltonian in the Control along a Stationary Mean-Field Triple
lemmalem:hamiltonian-quadratic-growth-2026aAnalysisMultivariable CalculusLet , , , with rate bound , with derivative bound , , , with second-derivative bound , , and be as in the definition of a stationary mean-field triple (the open set of t…Limits of Penalised Maxima on a Compact Subset of a Metric Space
lemmalem:doubling-limit-compact-metric-2026aAnalysisTopologyFor an upper semicontinuous and a nonnegative lower semicontinuous penalty on a compact set, the penalised maxima decrease to , the penalty vanishes along maximisers, and every cluster point maximises over the z…- Given upper semicontinuous summands on open sets and a test function whose difference with their sum has a local maximum, produces for each symmetric matrices that are admissible second-order test data from above for the summands, with block diagon…
Quadruple Approximable by Test-Function Data
definitiondef:approximable-by-test-data-2026aAnalysisPDEA quadruple of a point, value, vector and symmetric matrix is approximable by test data when it is the limit of data of test functions touching the function from above (or from below) at nearby points.Viscosity Inequalities Pass to Limits of Test-Function Data
lemmalem:viscosity-inequality-limit-test-data-2026bAnalysisPDEIf a second-order equation operator is continuous at a quadruple that is approximable by test data from above for a viscosity subsolution, the subsolution inequality holds at that quadruple; symmetrically from below for a supersolution.The Set of Symmetric Real Matrices is a Metric Space
lemmalem:symmetric-matrix-distance-is-metric-2026aAnalysisTopologyLinear AlgebraLet be a natural number, let be the set of symmetric real matrices, and let be the distance between symmetric real matrices. Then is a metric on , so that…Distance Between Symmetric Real Matrices
definitiondef:symmetric-matrix-distance-2026aAnalysisLinear AlgebraLet be a natural number, let be the real numbers, and let be the set of symmetric real matrices. For the difference is again symmetric by claim 1 of…A Sum in Separated Variables of Semiconvex Functions is Semiconvex
lemmalem:separated-sum-semiconvex-2026aAnalysisPDELet and be natural numbers and let be the real numbers with the order of their ordered field structure. For a natural number regard Euclidean space as a real vector space, with the sum of points, the scalar multiple and the…Perturbation Splitting of a Quadratic Form
lemmalem:quadratic-form-perturbation-split-2026aAnalysisLinear AlgebraPDELet be a natural number and let be the real numbers with the order of their ordered field structure. On Euclidean space , a real vector space, write for the sum of points, and for the difference and dot product,…Hessian Lower Bound for a Test Function Touching a Semiconvex Function from Above
lemmalem:semiconvex-upper-test-hessian-bound-2026aAnalysisPDEMultivariable CalculusLet be a natural number and let be the real numbers with the order of their ordered field structure. Regard Euclidean space as a real vector space, with the sum of points, the scalar multiple, and the…Restriction of a Cᵏ Function to an Open Subset
lemmalem:ck-restriction-open-subset-2026bMultivariable CalculusOn an open subset W of U, partial derivatives, differentiability and derivatives of a function are unchanged by restricting it to W, and restrictions of Cᵏ (smooth) functions are Cᵏ (smooth) on W.Transfer of a Test Function from the Sup-Convolution to the Original Function
lemmalem:sup-convolution-test-transfer-2026aPDELet , , and be as in Sup-Convolution of a Function on ; regard as a real vector space, with the sum of points, the scalar multiple and the difference . Let be the Euclidean distance, a…The Sup-Convolution Converges Pointwise to an Upper Semicontinuous Function
theoremthm:sup-convolution-pointwise-convergence-2026aAnalysisLet , , and be as in Sup-Convolution of a Function on , and let be the Euclidean distance, a metric on . Let be upper semicontinuous on with…The Sup-Convolution of an Upper Semicontinuous Function Attains its Supremum
lemmalem:sup-convolution-maximizer-2026aAnalysisLet , , and be as in Sup-Convolution of a Function on , and let be the Euclidean distance, a metric on . Let be upper semicontinuous on with…Domination, Monotonicity and Semiconvexity of the Sup-Convolution
lemmalem:sup-convolution-basic-properties-2026aAnalysisLet , , and be as in Sup-Convolution of a Function on , and let denote the dot product of points of . The set is a convex subset of itself, directly from that definit…