regression problems. We propose two new relations derived from the semantic distance between subtrees, known as semantic equivalence
and semantic similarity. These relations are used to guide variants of the crossover operator, resulting in two new crossover
operators—semantics aware crossover (SAC) and semantic similarity-based crossover (SSC). SAC, was introduced and previously
studied, is added here for the purpose of comparison and analysis. SSC extends SAC by more closely controlling the semantic
distance between subtrees to which crossover may be applied. The new operators were tested on some real-valued symbolic regression
problems and compared with standard crossover (SC), context aware crossover (CAC), Soft Brood Selection (SBS), and No Same
Mate (NSM) selection. The experimental results show on the problems examined that, with computational effort measured by the
number of function node evaluations, only SSC and SBS were significantly better than SC, and SSC was often better than SBS.
Further experiments were also conducted to analyse the perfomance sensitivity to the parameter settings for SSC. This analysis
leads to a conclusion that SSC is more constructive and has higher locality than SAC, NSM and SC; we believe these are the
main reasons for the improved performance of SSC.
- Content Type Journal Article
- Pages 91-119
- DOI 10.1007/s10710-010-9121-2
- Authors
- Nguyen Quang Uy, Complex & Adaptive Systems Lab, School of Computer Science & Informatics, University College Dublin, Dublin, Ireland
- Nguyen Xuan Hoai, Department of Computer Science, Le Quy Don University, Hanoi, Vietnam
- Michael O’Neill, Complex & Adaptive Systems Lab, School of Computer Science & Informatics, University College Dublin, Dublin, Ireland
- R. I. McKay, School of Computer Science and Engineering, Seoul National University, Seoul, Korea
- Edgar Galván-López, Complex & Adaptive Systems Lab, School of Computer Science & Informatics, University College Dublin, Dublin, Ireland
- Journal Genetic Programming and Evolvable Machines
- Online ISSN 1573-7632
- Print ISSN 1389-2576
- Journal Volume Volume 12
- Journal Issue Volume 12, Number 2