Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
Global Existence for the Backward Riccati Equation under Convexity Conditions
corollarycor:backward-riccati-convex-existence-2026bAnalysisLinear AlgebraLet be a real number and natural numbers. Let (), (), (), (), and () assign real matrices to each , all entries being continuous functions of , such that every and ever…The Separation Theorem for Partial-Information Linear-Quadratic-Gaussian Control
theoremthm:lqg-separation-theorem-2026bProbabilityThroughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…Existence and Self-Consistency of the Closed-Loop Feedback Control
lemmalem:closed-loop-feedback-control-2026bProbabilityConsider 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-2026bProbabilityThroughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…Integrals Against the Controlled Observations and the Controlled Filter Equation
lemmalem:controlled-observation-integrals-2026bProbabilityThroughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…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-2026bProbabilityThroughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…- Throughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…
Conditional Expectation and Estimation Error of the Controlled State
lemmalem:controlled-state-conditional-expectation-2026bProbabilityConsider 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-2026bProbabilityConsider 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-2026bProbabilityThroughout, a real-valued function on a subinterval of the real numbers is called continuous on when it is continuous relative to , both and the codomain carrying the metric of the real line. Consider a…Admissible Control for the Linear-Gaussian State-Observation Model
definitiondef:admissible-control-2026bProbabilityConsider 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…Product Rule and Reflection for Indefinite Riemann Integrals
lemmalem:riemann-product-rule-reflection-2026bAnalysisLet be real numbers. All integrals below are Riemann integrals of continuous functions — each interval being regarded as a subset of the real line with the absolute value metric and carrying the same metric — which exist by claim 3 of…- Let be a natural number and let be a symmetric positive definite real matrix. Then is invertible, and its inverse is symmetric positive definite.
Expected Bilinear Forms: Trace Formula and Mean-Square Continuity
lemmalem:expected-quadratic-form-2026bProbabilityLet be a probability space let be the real numbers, and let be natural numbers. A real-valued function defined on a closed interval is called continuous on when it is continuous relative to …- Let be natural numbers. Products below are matrix products, is the transpose, and is the trace. 1. (Linearity) For real matrices and real numbers , where denotes the entrywise linear combination:…
- Let be a natural number and let be a real matrix with entries (). The trace of is the real number the sum of the diagonal entries of .
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-2026bProbabilityConsider 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…