The busy beaver function (a.k.a. BB function or Radó's sigma function, denoted \(\Sigma(n)\) or \( ext{BB}(n)\)), is a distinctive fast-growing function from computability theory. It is notable as being the most well-known of the uncomputable functions. It is defined as the maximum number of ones that can be written (in the finished tape) with an n-state, 2-color halting Turing machine starting from a blank tape before halting.
Attributes | Values |
---|
rdf:type
| |
rdfs:label
| |
rdfs:comment
| - The busy beaver function (a.k.a. BB function or Radó's sigma function, denoted \(\Sigma(n)\) or \( ext{BB}(n)\)), is a distinctive fast-growing function from computability theory. It is notable as being the most well-known of the uncomputable functions. It is defined as the maximum number of ones that can be written (in the finished tape) with an n-state, 2-color halting Turing machine starting from a blank tape before halting.
|
dcterms:subject
| |
dbkwik:googology/p...iPageUsesTemplate
| |
Author
| |
Names
| - BB, Radó's sigma function
|
Year
| |
notation
| |
growthrate
| - >* all computable functions
|
abstract
| - The busy beaver function (a.k.a. BB function or Radó's sigma function, denoted \(\Sigma(n)\) or \( ext{BB}(n)\)), is a distinctive fast-growing function from computability theory. It is notable as being the most well-known of the uncomputable functions. It is defined as the maximum number of ones that can be written (in the finished tape) with an n-state, 2-color halting Turing machine starting from a blank tape before halting. Radó showed that this function eventually dominates all computable functions, and thus it is uncomputable. That is, no algorithm that terminates after a finite number of steps can compute \(\Sigma(n)\) for arbitrary \(n\). However, it is computable by an oracle Turing machine with an oracle for the halting problem. Turing machines that produce these numbers are called busy beavers. It is one of the fastest-growing functions ever arising out of professional mathematics. In googology, only a handful of significant functions surpass it — the xi function, the Rayo function, and the FOOT function.
|