Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
Almost-Everywhere Mean-Square Limits of Cauchy Sequences of Admissible Controls
lemmalem:control-sequence-mean-square-limit-2026aProbabilityConsider a linear-Gaussian state-observation model on with observation -algebras , let be a natural number, and let be a sequence of admissible controls with values in for the model. For adm…Restricted Lebesgue Measure and Integral Toolkit on a Compact Interval
lemmalem:interval-lebesgue-toolkit-2026aAnalysisProbabilityLet be real numbers, let be the Borel -algebra on , and let be Lebesgue measure, whose domain is by claim 3 of Existence of Lebesgue Measure on the Real Line. Define…The Separation Theorem for Partial-Information Linear-Quadratic-Gaussian Control
theoremthm:lqg-separation-theorem-2026aProbabilityConsider a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , and cost data with every positive definite; by Invertibility of Symmetric Positive Definite Matrices each exists and is symmet…Existence and Self-Consistency of the Closed-Loop Feedback Control
lemmalem:closed-loop-feedback-control-2026aProbabilityConsider the setting of Completion of Squares for the Linear-Quadratic-Gaussian Cost: a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , cost data with every positive definite, a symmetric continuou…Completion of Squares for the Linear-Quadratic-Gaussian Cost
theoremthm:lqg-completion-of-squares-2026aProbabilityConsider a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , and cost data such that additionally every is positive definite; by Invertibility of Symmetric Positive Definite Matrices each …Integrals Against the Controlled Observations and the Controlled Filter Equation
lemmalem:controlled-observation-integrals-2026aProbabilityConsider a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , an admissible control , and the controlled state and observations , , with notation and fixed versions as in those items. L…Orthogonal Decomposition of Expected Quadratic Forms under Independence
lemmalem:quadratic-form-independent-decomposition-2026aProbabilityLet be a probability space, let be a natural number, and let be a sub--algebra of . Let and be tuples of square-integrable random variables suc…Brownian Increments After a Time are Independent of the Model Past
lemmalem:brownian-increments-independent-model-past-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there. Fix and let denote the -algebra generated by the combined family of the random variables (), (…- Consider a linear-Gaussian state-observation model on , a control dimension , and a control matrix assignment as in Controlled State and Controlled Observations in the Linear-Gaussian Model. Cost data for this system is a name for a tuple of assignments (re…
Conditional Expectation and Estimation Error of the Controlled State
lemmalem:controlled-state-conditional-expectation-2026aProbabilityConsider a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , an admissible control , and the controlled state , with notation and fixed versions as in those items. Let and be…Superposition Decomposition of the Controlled State and Observations
lemmalem:controlled-state-superposition-2026aProbabilityConsider a linear-Gaussian state-observation model on , a control dimension , a control matrix assignment , an admissible control , and the controlled state and observations , , with all notation and fixed versions as in those item…Controlled State and Controlled Observations in the Linear-Gaussian Model
definitiondef:controlled-linear-gaussian-dynamics-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there; let be a natural number; let assign to each a real matrix whose entries are continuous functions of ; and let…Admissible Control for the Linear-Gaussian State-Observation Model
definitiondef:admissible-control-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there, and let be a natural number. An admissible control with values in for the model is a family , where each…Expected Bilinear Forms: Trace Formula and Mean-Square Continuity
lemmalem:expected-quadratic-form-2026aProbabilityLet be a probability space and let be natural numbers. Dot products are the dot product applied componentwise to tuples of random variables, matrix actions are the matrix-vector product, and is the trace. 1. (Trace formula)…Mean-Square Limits of Affine Combinations Adjoin to a Jointly Gaussian Family
lemmalem:gaussian-affine-span-closure-2026aProbabilityLet be a probability space, let be a jointly Gaussian family of random variables, and let be a family of square-integrable random variables such that every is a mean-square limit of finite affine combinations of mem…The Closed Mean-Square Span of a Family of Random Variables
lemmalem:mean-square-span-closure-2026aProbabilityLet be a probability space and let be a nonempty family of square-integrable random variables on it. Write , the closed mean-square span of , for the set of all square-integrable random variables fo…The Kalman-Bucy Filter Computes the Conditional Expectation in the Linear-Gaussian Model
theoremthm:kalman-bucy-conditional-expectation-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there, and let , , and the filter process be as in The Kalman-Bucy Filter Equation and Its Solution. Write (componentwise) for the…The Kalman-Bucy Filter Equation and Its Solution
theoremthm:kalman-bucy-filter-solution-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there. 1. (Covariance Riccati equation and gain) The matrix , with the covariance (defined and finite by…Integrals Against the Observation Process are Determined by the Observations
lemmalem:observation-stieltjes-adapted-2026aProbabilityConsider a linear-Gaussian state-observation model on , with notation and fixed versions as there. Let , let be a natural number, and let assign to each a real matrix with continuous entries. Define, for…Gaussian and Span Structure of the Linear-Gaussian State-Observation Model
lemmalem:observation-process-properties-2026aProbabilityConsider a linear-Gaussian state-observation model on , with all notation and fixed versions as there. 1. (Regularity and span structure) Each component family is mean-square continuous and almost surely. Moreover, for every …