Great Deluge

Gordon D.Pusch g_d_pusch_remove_underscores at xnet.com
Wed Nov 12 13:04:50 EST 2003


Chris Creevey <chris.creevey at may.ie> writes:

> 	I was wondering if anyone could describe the great deluge heuristic
> search of tree space please?

The "Great Deluge" imagines the scoring function to define a "landscape,"
and the acceptance threshold to define a "waterline" on that landscape.
The parameter values are allowed to "hop around" randomly on that "landscape,"
subject to the constraint that they may not get their "feet" wet.
"Rain" falls, the "water level" rises linearly, and the parameter values
are constrained to hop around on smaller and smaller "islands," until they
become "trapped on a peak." If they are lucky, they hopped across an "isthmus"
before the "rain" covered it over, and the "peak" they finally wind up on
is the "main island" instead of some little bitty rock just off the coastline...

That's the "Great Deluge" in a nutshell.


-- Gordon D. Pusch

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