47 lines
1.4 KiB
Plaintext
47 lines
1.4 KiB
Plaintext
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%%%%
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%%%% Decision of the direction by a coin tossing -- direction.psm
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%%%%
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%%%% This program has just one random switch named `coin'.
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%%%%
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%%%% Copyright (C) 2004,2006,2008
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%%%% Sato Laboratory, Dept. of Computer Science,
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%%%% Tokyo Institute of Technology
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%%-------------------------------------
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%% Sample session
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%%
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%% (1) Load this program:
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%% ?- prism(direction).
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%%
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%% (2) Get a sample:
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%% ?- sample(direction(D)).
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%%
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%% (3) Display the information about the switch `coin':
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%% ?- show_sw.
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%%
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%% (4) Set the probability distribution to the switch `coin':
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%% ?- set_sw(coin,[0.7,0.3]).
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%%
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%% (5) Display the switch information again with the distribution set
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%% at step 4:
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%% ?- show_sw.
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%%
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%% (6) Get a sample again with the distribution set at step 4:
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%% ?- sample(direction(D)).
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%%
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%% [Note1]
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%% Since 1.9, without any extra settings, the probability distribution
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%% of every switch is set to a uniform distribution.
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%%
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%% [Note2]
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%% If you go (3) with skipping (2), nothing should be displayed. This
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%% is because any random switch will not be registered by the system until
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%% it is explicitly used or referred to.
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values(coin,[head,tail]). % The switch `coin' takes `head' or `tail' as its value
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direction(D):-
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msw(coin,Face), % Make a coin tossing
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( Face==head -> D=left ; D=right). % Decide the direction according to
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% the result of coin tossing
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