An abstract machine is a theoretical model that allows for a detailed and precise analysis of how a computer system functions.

Abstract machines are

  1. ”machines” because they allow step-by-step execution of programs;
  2. “abstract” because they ignore many aspects of actual (hardware) machines.

A typical abstract machine consists of a definition in terms of input, output, and the set of allowable operations used to turn the former into the latter.

One such example is the Turing machine.

See also: Lambda Calculus


  • Deterministic abstract machines
    • For some given allowable operation and some input, it always produces the same output.
  • Non-deterministic abstract machines
    • Non-deterministic algorithms are helpful for obtaining approximate answers when deriving a precise solution using a deterministic approach is difficult or costly.