Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
Euclidean Openness Agrees with Metric Openness on
theoremthm:euclidean-open-iff-metric-open-rn-2026aTopologyMultivariable CalculusLet , let , and let be the Euclidean distance on . Then is open in the Euclidean sense if and only if is open in the metric space .Euclidean Distance is a Metric on
theoremthm:euclidean-distance-is-metric-rn-2026aTopologyMultivariable CalculusLet . Then the Euclidean distance is a metric on .- Let . Consider the set appearing in the definition of open subsets of Euclidean space. For points in , define where den…
Permutation Rule for Wedge Products of Coordinate 1-Forms
theoremthm:permutation-rule-coordinate-wedge-forms-euclidean-2026aGeometryMultivariable CalculusLet , let be open, let , and let be a permutation in the sense of Permutation of the Set . Then the coordinate -forms from…Active Coordinate Coefficient Formula for the Exterior Derivative
theoremthm:active-coefficient-exterior-derivative-euclidean-2026aGeometryMultivariable CalculusLet with , let be open, let be a differential -form on , and fix strictly increasing indices Write in the coordinate expansion from…Derivative of a Coordinate Slice of a Function on a Euclidean Open Set
theoremthm:coordinate-slice-derivative-c1-euclidean-2026aAnalysisMultivariable CalculusLet , let be open, let be a map, let , and let . Let with , and assume that…Associativity of the Wedge Product of Differential Forms on Euclidean Space
theoremthm:associativity-wedge-differential-forms-euclidean-2026bGeometryMultivariable CalculusLet , let be open, let , let be a differential -form on , let be a differential -form on , and let be a differential -form on . Then…Stokes Theorem for Oriented Sub-Rectangles in Euclidean Space
theoremthm:stokes-oriented-sub-rectangles-euclidean-2026bAnalysisGeometryMultivariable CalculusLet with , let be an oriented -sub-rectangle of , let be open with , and let be a differential -form on . Then…Oriented k-Sub-Rectangle of Euclidean Space
definitiondef:oriented-k-sub-rectangle-euclidean-2026aGeometryMultivariable CalculusLet with . Choose strictly increasing indices choose real numbers for , and for each index choose a real number . Let…Integral of a Differential Form over an Oriented k-Sub-Rectangle in Euclidean Space
definitiondef:integral-form-oriented-k-sub-rectangle-euclidean-2026bAnalysisGeometryMultivariable CalculusLet with , let be an oriented -sub-rectangle of , let be open with , and let be a continuous differential -form on . Choose data as in…Boundary of an Oriented k-Sub-Rectangle in Euclidean Space
definitiondef:boundary-oriented-k-sub-rectangle-euclidean-2026aGeometryMultivariable CalculusLet with , and let be an oriented -sub-rectangle of . Choose data as in Oriented k-Sub-Rectangle of Euclidean Space, so that for a standard -rectangle…Standard k-Rectangle in Euclidean Space
definitiondef:standard-k-rectangle-euclidean-2026aGeometryMultivariable CalculusLet . A standard -rectangle in is a set of the form where and for every index .Exterior Derivative of a Differential Form on a Euclidean Open Set
definitiondef:exterior-derivative-c1-differential-form-euclidean-open-set-2026bGeometryMultivariable CalculusLet , let be open, let , and let be a differential -form on . Write as in…Differential k-Form on an Open Subset of Euclidean Space
definitiondef:c1-differential-k-form-euclidean-open-set-2026bGeometryMultivariable CalculusLet , let be open, let , and let be a differential -form on . Write in the coordinate expansion from Coordinate Expansion of Differential Forms on Euclidean Open Sets. We say that …Continuous Differential k-Form on an Open Subset of Euclidean Space
definitiondef:continuous-differential-k-form-euclidean-open-set-2026bGeometryMultivariable CalculusLet , let be open, let , and let be a differential -form on . Write in the coordinate expansion from Coordinate Expansion of Differential Forms on Euclidean Open Sets. We say that …Coordinate Expansion of Differential Forms on Euclidean Open Sets
theoremthm:coordinate-expansion-differential-forms-euclidean-2026bGeometryMultivariable CalculusLet , let be open, let , and let be a differential -form on . Then there exist unique real-valued functions indexed by strictly increasing -tuples…Coordinate 1-Form on an Open Subset of Euclidean Space
definitiondef:coordinate-1-form-euclidean-open-set-2026aGeometryMultivariable CalculusLet , let be open, and let . The th coordinate -form on is the differential -form on defined by for every point and every vector…Maps on Euclidean Open Sets are Differentiable
theoremthm:c1-implies-differentiable-euclidean-2026aMultivariable CalculusLet . Let be open, and let be a map. Then for every point , the map is differentiable at .Composition of Continuous Euclidean Maps
theoremthm:composition-continuous-euclidean-2026aMultivariable CalculusLet . Let , let , let , and let . Let . Suppose that is continuous at and that is continuous at . Then the composition is cont…Coordinatewise Characterization of Continuity for Euclidean Maps
theoremthm:continuous-coordinatewise-euclidean-2026aMultivariable CalculusLet . Let , let , and let . Then the following are equivalent. 1. The map is continuous at . 2. For every index , the coordinate function is cont…