page_title: Matchbox Educable Noughts and Crosses Engine
section_title: Correlation
hierarchical_section_title: Matchbox Educable Noughts and Crosses Engine / Results in practice / Correlation
caption_attribution_description: English: This graph shows the results of Donald Michie's games against MENACE. This is a recreation of a graph that was published in Michie's 1961 article Trial and error in Penguin Science Survey 2.
context_page_description: The Matchbox Educable Noughts and Crosses Engine or MENACE was an analogue computer made up of 304 matchboxes designed and built by Donald Michie in 1961. It was designed to play human opponents in games of noughts and crosses by returning a move for any given state of play and to refine its strategy through reinforcement learning.
  Computer equipment was not readily available for non-government use, so Michie worked around this restriction by building it out of matchboxes.The matchboxes used by Michie each represented a single possible layout of a Noughts and Crosses grid. When the computer first played, it would randomly choose moves based on the current layout. As it played more games, through a reinforcement loop, it disqualified strategies that led to losing games, and supplemented strategies that led to winning games. Michie held a tournament against MENACE in 1961, wherein he experimented with different openings.
  Following MENACE's maiden tournament against Michie, it was shown to be a successful computer. Michie's essays on MENACE's weight initialisation and the BOXES algorithm used by MENACE became popular in the field of computer science research.
context_section_description: Depending on the strategy employed by the human player, MENACE produces a different trend on scatter graphs of wins. Using a random turn from the human player results in an almost-perfect positive trend. Playing the optimal strategy returns a slightly slower increase. The reinforcement does not create a perfect standard of wins; the algorithm will draw random uncertain conclusions each time. After the jth The correlation of near-perfect play runs:
  Where Vᵢ is the outcome (+1 is win, 0 is draw and -1 is loss) D is the Decay Factor (average of past values of wins and losses). Below, Mₙ is the multiplier for the nth round of the game.
caption: Scatter graph of Michie's tournament.
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