Computable functions are the basic objects of study in computability theory. Informally, a function is computable if there is an algorithm that computes...
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if it is not computable. A subset S {\displaystyle S} of the natural numbers is computable if there exists a total computable function f {\displaystyle...
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the recursive numbers, effective numbers, computable reals, or recursive reals. The concept of a computable real number was introduced by Émile Borel...
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Busy beaver (redirect from Busy beaver function)
"On Non-Computable Functions". One of the most interesting aspects of the busy beaver game is that, if it were possible to compute the functions Σ(n) and...
66 KB (7,986 words) - 10:52, 2 August 2025
recursive function, partial recursive function, or μ-recursive function is a partial function from natural numbers to natural numbers that is "computable" in...
18 KB (2,747 words) - 19:37, 29 July 2025
Turing machine (redirect from Turing-computable function)
ideas leads to the author's definition of a computable function, and to an identification of computability with effective calculability. It is not difficult...
73 KB (9,384 words) - 09:54, 29 July 2025
with the study of computable functions and Turing degrees. The field has since expanded to include the study of generalized computability and definability...
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Church–Turing thesis (category Computability theory)
of computable functions. It states that a function on the natural numbers can be calculated by an effective method if and only if it is computable by...
58 KB (6,849 words) - 09:27, 20 July 2025
Log-space reduction (redirect from Log-space computable function)
important property of logspace computability is that, if functions f , g {\displaystyle f,g} are logspace computable, then so is their composition g...
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exponential function, and the function which returns the nth prime are all primitive recursive. In fact, for showing that a computable function is primitive...
40 KB (7,348 words) - 09:34, 30 July 2025
Computation in the limit (redirect from Limit-computable)
computability theory, a function is called limit computable if it is the limit of a uniformly computable sequence of functions. The terms computable in...
9 KB (1,678 words) - 02:57, 26 July 2024
Halting problem (category Computability theory)
often in discussions of computability since it demonstrates that some functions are mathematically definable but not computable. A key part of the formal...
53 KB (7,350 words) - 09:57, 12 June 2025
Logic for Computable Functions (LCF) is an interactive automated theorem prover developed at Stanford and Edinburgh by Robin Milner and collaborators in...
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pairing function) are computably enumerable sets. The preimage of a computably enumerable set under a partial computable function is a computably enumerable...
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total computable function that is not primitive recursive. All primitive recursive functions are total and computable, but the Ackermann function illustrates...
62 KB (7,410 words) - 11:24, 23 June 2025
Decider (Turing machine) (redirect from Decider (computability theory))
partial function computable by a partial Turing machine be extended (that is, have its domain enlarged) to become a total computable function? Is it possible...
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function may refer to: Recursive function (programming), a function which references itself General recursive function, a computable partial function...
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Kleene's recursion theorem (category Computability theory)
In computability theory, Kleene's recursion theorems are a pair of fundamental results about the application of computable functions to their own descriptions...
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acceptable definition of a computable function defines also the same functions. General recursive functions are partial functions from integers to integers...
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recognize. The domain of any universal computable function is a computably enumerable set but never a computable set. The domain is always Turing equivalent...
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a Turing machine. Hypercomputers compute functions that a Turing machine cannot and which are, hence, not computable in the Church–Turing sense. Technically...
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Lambda calculus (redirect from Lambda-definable function)
usual for such a proof, computable means computable by any model of computation that is Turing complete. In fact computability can itself be defined via...
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science, Programming Computable Functions (PCF), or Programming with Computable Functions, or Programming language for Computable Functions, is a programming...
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arbitrary function with domain ω and only countably many computable functions. A specific example of a set with an enumeration but not a computable enumeration...
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Aleph number (redirect from Aleph function)
the set of all algebraic numbers, the set of all computable numbers, the set of all computable functions, the set of all binary strings of finite length...
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UTM theorem (redirect from Universal Function)
numbering of the computable functions in terms of the smn theorem and the UTM theorem. The theorem states that a partial computable function u of two variables...
2 KB (242 words) - 01:42, 26 January 2024
Kolmogorov complexity (category Computability theory)
2^{*}} be a computable function mapping finite binary strings to binary strings. It is a universal function if, and only if, for any computable f : 2 ∗ →...
60 KB (7,896 words) - 07:35, 21 July 2025
Arity (redirect from 0-ary function)
science, arity (/ˈærɪti/ ) is the number of arguments or operands taken by a function, operation or relation. In mathematics, arity may also be called rank,...
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computability theory, a function f : R → R {\displaystyle f\colon \mathbb {R} \to \mathbb {R} } is sequentially computable if, for every computable sequence...
2 KB (334 words) - 20:47, 27 April 2020
Fast-growing hierarchy (category Hierarchy of functions)
a total function. If the fundamental sequences are computable (e.g., as in the Wainer hierarchy), then every fα is a total computable function. In the...
14 KB (1,602 words) - 15:19, 22 June 2025