Schush: trivial geography, historically assessed hardness, and other goodies
January 2, 2010by Lee Spector (lspector)
A bigger update for the new year:
http://hampshire.edu/lspector/schush.ss
The biggest additions are trivial geography (which was trivial to add 🙂 but which can make a big difference) and error scaling using one form of historically assessed hardness. Here’s the full list of new changes:
20091229: - Added scale-errors parameter to schushgp; when #t this calculates scaled errors via the Historically Assessed Hardness (HAH) method (in the "current generation / quotient" setting) and uses these scaled errors as the basis of selection. HAH is described in: Klein, J., and L. Spector. 2008. Genetic Programming with Historically Assessed Hardness. In Genetic Programming Theory and Practice VI, edited by R. L. Riolo, T. Soule, and B. Worzel, pp. 61-74. New York: Springer-Verlag. http://hampshire.edu/lspector/pubs/kleinspector-gptp08-preprint.pdf This form of HAH is similar but non-identical (for non-Boolean problems) to "implicit fitness sharing" as described by McKay in: McKay, R. I. 2001. An investigation of fitness sharing in genetic programming. The Australian J. of Intelligent Information Processing Systems, 7(1/2):43–51. Also added examples using the scale-errors parameter. - Added three schushgp parameters to control the number of iterations of automatic simplification performed at various times: - report-simplifications: the number performed for each schushgp generation report - final-report-simplifications: the number performed on successful results - reproduction-simplifications: the number performed by the simplification genetic operator - Fixed bug in cases for factorial example. - Added YANK and YANKDUP instructions for all types. 20100102: - Added trivial geography, controlled by a trivial-geography-radius parameter to schushgp; set this to zero (the default) for no trivial geography. Trivial geography is described in: Spector, L., and J. Klein. 2005. Trivial Geography in Genetic Programming. In Genetic Programming Theory and Practice III, edited by T. Yu, R.L. Riolo, and B. Worzel, pp. 109-124. Boston, MA: Kluwer Academic Publishers. http://hampshire.edu/lspector/pubs/trivial-geography-toappear.pdf Also added an example using trivial geography. - Made several minor corrections to the documentation.