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  2. List of undecidable problems - Wikipedia

    en.wikipedia.org/wiki/List_of_undecidable_problems

    For functions in certain classes, the problem of determining: whether two functions are equal, known as the zero-equivalence problem (see Richardson's theorem); [5] the zeroes of a function; whether the indefinite integral of a function is also in the class. [6] Of course, some subclasses of these problems are decidable.

  3. David Makinson - Wikipedia

    en.wikipedia.org/wiki/David_Makinson

    Among his contributions: in 1965, as a graduate student, he identified the preface paradox [3] and adapted the method of maximal consistent sets for proving completeness results in modal logic [citation needed]; in 1969 he discovered the first simple and natural propositional logic lacking the finite model property [citation needed]; in the ...

  4. Logic puzzle - Wikipedia

    en.wikipedia.org/wiki/Logic_puzzle

    Another form of logic puzzle, popular among puzzle enthusiasts and available in magazines dedicated to the subject, is a format in which the set-up to a scenario is given, as well as the object (for example, determine who brought what dog to a dog show, and what breed each dog was), certain clues are given ("neither Misty nor Rex is the German Shepherd"), and then the reader fills out a matrix ...

  5. List of unsolved problems in mathematics - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Many mathematical problems have been stated but not yet solved. These problems come from many areas of mathematics, such as theoretical physics, computer science, algebra, analysis, combinatorics, algebraic, differential, discrete and Euclidean geometries, graph theory, group theory, model theory, number theory, set theory, Ramsey theory, dynamical systems, and partial differential equations.

  6. Boolean satisfiability problem - Wikipedia

    en.wikipedia.org/wiki/Boolean_satisfiability_problem

    WMSAT is the problem of finding an assignment of minimum weight that satisfy a monotone Boolean formula (i.e. a formula without any negation). Weights of propositional variables are given in the input of the problem. The weight of an assignment is the sum of weights of true variables. That problem is NP-complete (see Th. 1 of [26]).

  7. Monadic second-order logic - Wikipedia

    en.wikipedia.org/wiki/Monadic_second-order_logic

    The satisfiability problem for monadic second-order logic is undecidable in general because this logic subsumes first-order logic. The monadic second-order theory of the infinite complete binary tree, called S2S, is decidable. [8] As a consequence of this result, the following theories are decidable: The monadic second-order theory of trees.

  8. Hilbert's second problem - Wikipedia

    en.wikipedia.org/wiki/Hilbert's_second_problem

    In mathematics, Hilbert's second problem was posed by David Hilbert in 1900 as one of his 23 problems. It asks for a proof that arithmetic is consistent – free of any internal contradictions. Hilbert stated that the axioms he considered for arithmetic were the ones given in Hilbert (1900) , which include a second order completeness axiom.

  9. Stanhope Demonstrator - Wikipedia

    en.wikipedia.org/wiki/Stanhope_Demonstrator

    The Stanhope Demonstrator was the first machine to solve problems in logic. [1] It was designed by Charles Stanhope, 3rd Earl Stanhope to demonstrate consequences in logic symbolically. The first model was constructed in 1775. It consisted of two slides coloured red and gray mounted in a square brass frame.