Problem instances
A computational problem can be viewed as an infinite collection of instances together with a set (possibly empty) of solutions for every … See more

Defining complexity classes
A complexity class is a set of problems of related complexity. Simpler complexity classes are defined … See more

A problem that can theoretically be solved, but requires impractical and finite resources (e.g., time) to do so, is known as an intractable problem. Conversely, a problem that can be solved in practice is called a tractable problem, literally "a problem that can … See more

An early example of algorithm complexity analysis is the running time analysis of the Euclidean algorithm done by Gabriel Lamé in 1844.
Before the actual … See more

Turing machine
A Turing machine is a mathematical model of a general computing machine. It is a theoretical device that manipulates symbols contained on a strip of tape. Turing machines are not intended as a practical computing … See more

P versus NP problem
The complexity class P is often seen as a mathematical abstraction modeling those computational tasks that admit an efficient algorithm. This hypothesis is called the Cobham–Edmonds thesis. The complexity class See more

Continuous complexity theory can refer to complexity theory of problems that involve continuous functions that are approximated by discretizations, as studied in See more