Model of computation

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For another meaning, see Computational model

A model of computation is a term from the theory of computations: computability theory and computational complexity theory.

A model of computation is the definition of the set of allowable operations used in computation and their respective costs. Only assuming a certain model of computation it is possible to analyze the computational resources required, such as the execution time or memory space or to discuss the limitations of algorithms or computers.

In discussing asymptotic estimates of computational complexity, it is common to specify a computational model in terms of primitive operations allowed which have unit cost, or simply unit-cost operations.

There are many models of computation, differing in the set of admissible operations and their computations cost. They fall into the following broad categories: abstract machine (abstract computer), used in proofs of computability and upper bounds on computational complexity of algorithms, and decision tree models, used in proofs of lower bounds on computational complexity of algorithmic problems.