Manual de Houdini 3 2012 | Page 242

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Houdini Help
(e.g. Shredder, Fritz) wait for sending the button command to the engine until you
click OK in the engine options window.
The size of the file will be identical to the size of the hash memory, so this operation
could take a while. This feature can be used to interrupt and restart a deep analysis
at any time.
Load Hash from File (button)
Load a previously saved hash file from disk.
Use the Load Hash from File button after loading the game or position, but before
starting the analysis. Some GUIs (e.g. Shredder, Fritz) wait for sending the button
command to the engine until you click OK in the engine options window.
The size of the hash memory will automatically be set to the size of the saved file.
Please make sure to check the Never Clear Hash option, as otherwise your loaded
Hash could be cleared by a subsequent ucinewgame or Clear Hash command.

Position Learning
With Posit ion Le a rning Houdini will remember advantageous principal variations it has
analyzed by storing them in a learning disk file, for reuse in later games or analysis.
The feature is completely transparent to the user, once Learning is enabled the data
will be saved and loaded automatically.
The Position Learning is available in analysis and match play. But remember that it will
only kick in for certain positions in which there is something to learn, i.e. when the
score is significantly above the static evaluation of the position. In quiet, equal
positions there's usually not much to learn.
Position Learning works best for positions where a good move exists that raises the
score significantly above the statical evaluation. Learning is less useful and sometimes
counterproductive for positions where many more or less equivalent moves exist and
the goal is to avoid bad moves. To improve the efficiency of the learning the feature
only kicks in when a certain positive scoring threshold is exceeded. By default this
Learning Thr eshold is put at 10 centi-pawn (0.1 pawn).
Although the learning file grows very slowly, make sure not to allow the file to grow
too large as the automatic loading may slow down the engine at the start of the
analysis.
The impact of Position Learning can be illustrated as follows.
When running the Eigenmann Ending Test Suite with 20 seconds/move on a single-core
laptop producing about 1,000 kN/s, Houdini finds 77 out of 100 solutions, the total
solution time is 12:06. The test run produces a Learning File of about 27 kB. Running
the Test Suite a second time demonstrates the profit of the Learning File. Houdini now
finds 80 solutions and the total solution time drops to 9:42.
Learning (checkbox)

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