Droste effect
The Droste effect (Dutch pronunciation: [ˈdrɔstə]), known in art as an example of mise en abyme, is the effect of a picture recursively appearing within itself, in a place where a similar picture woul
Gestalt pattern matching
Gestalt pattern matching, also Ratcliff/Obershelp pattern recognition, is a string-matching algorithm for determining the similarity of two strings. It was developed in 1983 by John W. Ratcliff and an
When Fiction Lives in Fiction
When Fiction Lives in Fiction is the title of a significant narrative essay written in 1939 by the Argentinian writer Jorge Luis Borges. Weighing in at something less than three pages in length, Borge
Primitive recursive function
In computability theory, a primitive recursive function is roughly speaking a function that can be computed by a computer program whose loops are all "for" loops (that is, an upper bound of the number
Recursion (computer science)
In computer science, recursion is a method of solving a computational problem where the solution depends on solutions to smaller instances of the same problem. Recursion solves such recursive problems
Mutual recursion
In mathematics and computer science, mutual recursion is a form of recursion where two mathematical or computational objects, such as functions or datatypes, are defined in terms of each other. Mutual
Primitive recursive set function
In mathematics, primitive recursive set functions or primitive recursive ordinal functions are analogs of primitive recursive functions, defined for sets or ordinals rather than natural numbers. They
Anonymous recursion
In computer science, anonymous recursion is recursion which does not explicitly call a function by name. This can be done either explicitly, by using a higher-order function – passing in a function as
Double recursion
In recursive function theory, double recursion is an extension of primitive recursion which allows the definition of non-primitive recursive functions like the Ackermann function. Raphael M. Robinson
Recursive language
In mathematics, logic and computer science, a formal language (a set of finite sequences of symbols taken from a fixed alphabet) is called recursive if it is a recursive subset of the set of all possi
Transfinite induction
Transfinite induction is an extension of mathematical induction to well-ordered sets, for example to sets of ordinal numbers or cardinal numbers. Its correctness is a theorem of ZFC.
Reentrancy (computing)
In computing, a computer program or subroutine is called reentrant if multiple invocations can safely run concurrently on multiple processors, or on a single processor system, where a reentrant proced
Left recursion
In the formal language theory of computer science, left recursion is a special case of recursion where a string is recognized as part of a language by the fact that it decomposes into a string from th
Corecursion
In computer science, corecursion is a type of operation that is dual to recursion. Whereas recursion works analytically, starting on data further from a base case and breaking it down into smaller dat
Recursive islands and lakes
A recursive island or lake is an island or a lake that lies within a lake or an island.For the purposes of defining recursion, small continental land masses such as Madagascar and New Zealand count as
Recursive definition
In mathematics and computer science, a recursive definition, or inductive definition, is used to define the elements in a set in terms of other elements in the set (Aczel 1977:740ff). Some examples of
Hierarchical and recursive queries in SQL
A hierarchical query is a type of SQL query that handles hierarchical model data. They are special cases of more general recursive fixpoint queries, which compute transitive closures. In standard SQL:
Impredicativity
In mathematics, logic and philosophy of mathematics, something that is impredicative is a self-referencing definition. Roughly speaking, a definition is impredicative if it invokes (mentions or quanti
Recursive acronym
A recursive acronym is an acronym that refers to itself, and appears most frequently in computer programming. The term was first used in print in 1979 in Douglas Hofstadter's book Gödel, Escher, Bach:
Course-of-values recursion
In computability theory, course-of-values recursion is a technique for defining number-theoretic functions by recursion. In a definition of a function f by course-of-values recursion, the value of f(n
Tail call
In computer science, a tail call is a subroutine call performed as the final action of a procedure. If the target of a tail is the same subroutine, the subroutine is said to be tail recursive, which i
Walther recursion
In computer programming, Walther recursion (named after Christoph Walther) is a method of analysing recursive functions that can determine if the function is definitely terminating, given finite input
Polymorphic recursion
In computer science, polymorphic recursion (also referred to as Milner–Mycroft typability or the Milner–Mycroft calculus) refers to a recursive parametrically polymorphic function where the type param
Tree traversal
In computer science, tree traversal (also known as tree search and walking the tree) is a form of graph traversal and refers to the process of visiting (e.g. retrieving, updating, or deleting) each no
Bar recursion
Bar recursion is a generalized form of recursion developed by C. Spector in his 1962 paper. It is related to bar induction in the same fashion that primitive recursion is related to ordinary induction
Fold (higher-order function)
In functional programming, fold (also termed reduce, accumulate, aggregate, compress, or inject) refers to a family of higher-order functions that analyze a recursive data structure and through use of
Fixed-point combinator
In mathematics and computer science in general, a fixed point of a function is a value that is mapped to itself by the function. In combinatory logic for computer science, a fixed-point combinator (or
Nonrecursive filter
In mathematics, a nonrecursive filter only uses input values like x[n − 1], unlike recursive filter where it uses previous output values like y[n − 1]. In signal processing, non-recursive digital filt
Recursion
Recursion (adjective: recursive) occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common appl
Infinite loop
In computer programming, an infinite loop (or endless loop) is a sequence of instructions that, as written, will continue endlessly, unless an external intervention occurs ("pull the plug"). It may be