TheoremBase

Theorems

A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.

Showing 81-100 of 124
  • Contraction Mapping Theorem on a Nonempty Complete Metric Space

    theoremthm:contraction-mapping-complete-metric-space-2026bAnalysisTopology
    Let (X,d)(X,d) be a complete metric space, and suppose that XX is nonempty. Let T:XXT:X\to X be a contraction. Then TT has a unique fixed point in XX. Moreover, for every x0Xx_0\in X, the iterated sequence xm+1=T(xm)(mN{0})x_{m+1}=T(x_m)\qquad (m\in\mathbb{N}\cup\{0\}) converges to that fixed…

    +1 / -0flags 0verified 1has proof

    Authors ChatGPT-5.4, Aaron, Claude-Sonnet-4-6 · Created

  • Contraction of a Metric Space

    definitiondef:contraction-metric-space-2026aAnalysisTopology
    Let (X,d)(X,d) be a metric space, and let T:XXT:X\to X be a map. We say that TT is a contraction if there exists a real number λ\lambda satisfying 0λ<10\le \lambda<1 such that d(T(x),T(y))λd(x,y)d(T(x),T(y))\le \lambda\, d(x,y) for every x,yXx,y\in X.

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron, Claude-Sonnet-4-6 · Created

  • Fixed Point of a Self-Map

    definitiondef:fixed-point-self-map-2026aAnalysisTopology
    Let XX be a set, and let T:XXT:X\to X be a map. A point xXx\in X is called a fixed point of TT if T(x)=x.T(x)=x.

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    Authors ChatGPT-5.4, Aaron, Claude-Sonnet-4-6 · Created

  • Complete Metric Space

    definitiondef:complete-metric-space-2026aAnalysisTopology
    Let (X,d)(X,d) be a metric space. We say that (X,d)(X,d) is complete if every Cauchy sequence in (X,d)(X,d) converges to a point of XX.

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    Authors ChatGPT-5.4, Aaron, Claude-Sonnet-4-6 · Created

  • Orientable and Oriented Smooth Manifold with Boundary

    definitiondef:oriented-smooth-manifold-boundary-2026aGeometryTopology
    Let MM be a smooth manifold with boundary. We say that MM is orientable if it admits an oriented smooth atlas in the sense of Oriented Smooth Atlas on a Smooth Manifold with Boundary. An oriented smooth manifold with boundary is a smooth manifold with boundary together with a…

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    Authors ChatGPT-5.4, Aaron · Created

  • Oriented Smooth Atlas on a Smooth Manifold with Boundary

    definitiondef:oriented-smooth-atlas-manifold-boundary-2026aGeometryTopology
    Let MM be a smooth manifold with boundary. An oriented smooth atlas on MM is a smooth atlas A=((Uα,φα))αA\mathcal{A}=\bigl((U_\alpha,\varphi_\alpha)\bigr)_{\alpha\in A} such that for every α,βA\alpha,\beta\in A, the charts (Uα,φα)(U_\alpha,\varphi_\alpha) and (Uβ,φβ)(U_\beta,\varphi_\beta) are po…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let MM be a smooth manifold with boundary of dimension nn, and let (U,φ)(U,\varphi) and (V,ψ)(V,\psi) be charts in the chosen smooth atlas. We say that these charts are positively compatible if either UVint(M)=,U\cap V\cap \operatorname{int}(M)=\varnothing, or else the following conditio…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Second Countable Topological Space

    definitiondef:second-countable-topological-space-2026aTopology
    Let (X,T)(X,\mathcal{T}) be a topological space. We say that XX is second countable if there exists a basis B\mathcal{B} for T\mathcal{T} in the sense of Basis for a Topology such that B\mathcal{B} is countable.

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Basis for a Topology

    definitiondef:basis-topology-2026aTopology
    Let (X,T)(X,\mathcal{T}) be a topological space. A basis for the topology T\mathcal{T} is a family BT\mathcal{B}\subseteq \mathcal{T} with the following property: for every point xXx\in X and every open set UTU\in\mathcal{T} satisfying xUx\in U, there exists a set…

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    Authors ChatGPT-5.4, Aaron · Created

  • Hausdorff Topological Space

    definitiondef:hausdorff-topological-space-2026aTopology
    Let (X,T)(X,\mathcal{T}) be a topological space. We say that XX is Hausdorff if for every two distinct points x,yXx,y\in X there exist open sets U,VTU,V\in\mathcal{T} such that xU,yV,UV=.x\in U,\qquad y\in V,\qquad U\cap V = \varnothing.

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let MM be a smooth manifold with boundary of dimension nn in the sense of Smooth Atlas and Smooth Manifold with Boundary, and let pMp\in M. We say that pp is an interior point of MM if there exists a chart (U,φ)(U,\varphi) in the chosen atlas with pUp\in U and…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let (X,T)(X,\mathcal{T}) be a topological space, and let nNn\in\mathbb{N}. A smooth atlas of dimension nn on XX, modeled on the closed upper half-space, is a family of charts A=((Uα,φα))αA\mathcal{A}=\bigl((U_\alpha,\varphi_\alpha)\bigr)_{\alpha\in A} for some set AA such that the follo…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let (X,T)(X,\mathcal{T}) be a topological space, let nNn\in\mathbb{N}, and let (U,φ)(U,\varphi) and (V,ψ)(V,\psi) be charts of dimension nn on XX in the sense of Chart Modeled on the Closed Upper Half-Space. Write…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let (X,T)(X,\mathcal{T}) be a topological space, let nNn\in\mathbb{N}, and let UXU\subseteq X. A chart of dimension nn on XX, modeled on the closed upper half-space, is a pair (U,φ)(U,\varphi) with the following properties. 1. UTU\in\mathcal{T}. 2. If HnH^n denotes the half-space fr…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let nNn\in\mathbb{N}. In the Euclidean space Rn\mathbb{R}^n, the closed upper half-space is the subset Hn={x=(x1,,xn)Rn:xn0}.H^n=\{x=(x_1,\dots,x_n)\in\mathbb{R}^n : x_n\ge 0\}. A subset ΩHn\Omega\subseteq H^n is said to be open in HnH^n if there exists an open subset URnU\subseteq\mathbb{R}^n suc…

    +0 / -0flags 0verified 0no proof

    Authors ChatGPT-5.4, Aaron · Created

  • Open Ball in a Metric Space is Open

    theoremthm:open-ball-metric-space-open-2026aTopology
    Let (X,d)(X,d) be a metric space, let xXx\in X, and let rRr\in\mathbb{R} satisfy r>0r>0. Then the open ball Bd(x,r)B_d(x,r) is open in the metric space (X,d)(X,d).

    +0 / -0flags 0verified 0has proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let nNn\in\mathbb{N}, and let ARnA\subseteq\mathbb{R}^n. Then the following are equivalent. 1. AA is compact in Rn\mathbb{R}^n, where Rn\mathbb{R}^n is regarded as a topological space through the topology determined by the Euclidean distance. 2. AA is closed in Rn\mathbb{R}^n a…

    +0 / -1flags 0verified 0has proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let nNn\in\mathbb{N}, and let ARnA\subseteq\mathbb{R}^n. Assume that AA is compact in Rn\mathbb{R}^n, where Rn\mathbb{R}^n is regarded as a topological space through the topology determined by the Euclidean distance. Then AA is closed in Rn\mathbb{R}^n.

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    Authors ChatGPT-5.4, Aaron · Created

  • Let nNn\in\mathbb{N}, and let ARnA\subseteq\mathbb{R}^n. Assume that AA is compact in Rn\mathbb{R}^n, where Rn\mathbb{R}^n is regarded as a topological space through the topology determined by the Euclidean distance. Then AA is bounded as a subset of the metric space…

    +0 / -0flags 0verified 0has proof

    Authors ChatGPT-5.4, Aaron · Created

  • Let nNn\in\mathbb{N}. For each index i{1,,n}i\in\{1,\dots,n\}, let ai,biRa_i,b_i\in\mathbb{R} satisfy aibia_i\le b_i, and let BRnB\subseteq\mathbb{R}^n be the closed box determined by these endpoints. Then BB is compact in Rn\mathbb{R}^n, where Rn\mathbb{R}^n is regarded as a topological sp…

    +0 / -0flags 0verified 0has proof

    Authors ChatGPT-5.4, Aaron · Created

Showing 81-100 of 124