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  1. Propositions As Types Analogy • 1
    inquiryintoinquiry.com/2013/01

    One of my favorite mathematical tricks — it almost seems too tricky to be true — is the Propositions As Types Analogy. And I see hints the 2‑part analogy can be extended to a 3‑part analogy, as follows.

    Proof Hint ∶ Proof ∶ Proposition

    Untyped Term ∶ Typed Term ∶ Type

    or

    Proof Hint ∶ Untyped Term

    Proof ∶ Typed Term

    Proposition ∶ Type

    See my working notes on the Propositions As Types Analogy —
    oeis.org/wiki/Propositions_As_

    #Mathematics #CategoryTheory #ProofTheory #TypeTheory
    #Logic #Analogy #Isomorphism #PropositionalCalculus
    #CombinatorCalculus #CombinatoryLogic #LambdaCalculus
    #Peirce #LogicalGraphs #GraphTheory #RelationTheory

  2. There are two ways to view a computer program. The first one is the execution-oriented view, in which a program is a sequence of steps that are executed by a computer. The second is the problem-oriented view, where a program solves a problem by a combination of executing elementary steps and calling subprograms that solve subproblems.

    The earliest model for the execution-oriented view is the Turing machine, and that for the problem-oriented view is the lambda calculus.

    This explains why execution-oriented questions like computational complexity are described and solved in terms of Turing machines, while all programming languages that are used in the real world have the function-calling structure of the lambda calculus.

    #Computation #TuringMachine #LambdaCalculus #ProgrammingLanguages

  3. Survey of Precursors Of Category Theory
    inquiryintoinquiry.com/2023/04

    A few years ago I began a sketch on the “Precursors of Category Theory”, tracing the continuities of the category concept from Aristotle, to Kant and Peirce, through Hilbert and Ackermann, to contemporary mathematical practice. A Survey of resources on the topic is given below, still very rough and incomplete, but perhaps a few will find it of use.

    #CategoryTheory #CombinatoryLogic #LambdaCalculus #RelationTheory
    #Aristotle #Kant #Peirce #Schönfinkel #Hilbert #Ackermann #Carnap
    #HaskellCurry #WilliamHoward #JoachimLambek #SaundersMacLane
    #PropositionsAsTypesAnalogy #CurryHowardIsomorphism #Ulam