Evolving recursive programs using non-recursive scaffolding

Abstract

Abstract-Genetic programming has proven capable of evolving solutions to a wide variety of problems. However, the successes have largely been with programs without iteration or recursion; evolving recursive programs has turned out to be particularly challenging. The main obstacle to evolving recursive programs seems to be that they are particularly fragile to the application of search operators: a small change in a correct recursive program generally produces a completely wrong program. In this paper, we present a simple and general method that allows us to pass back and forth from a recursive program to an associated nonrecursive program. Finding a recursive program can be reduced to evolving non-recursive programs followed by converting the optimum non-recursive program found to the associated optimum recursive program. This avoids the fragility problem above, as evolution does not search the space of recursive programs. We present promising experimental results on a test-bed of recursive problems.

Stochastic synthesis of recursive functions made easy with bananas, lenses, envelopes and barbed wire

“…that even a minute modification of a recursive function may drastically affect the course of recursion calls and so impair candidate program quality. That brittleness has been pointed to in numerous past works on GP for recursive functions (see, e.g., [4,23,24,40]). The well-foundedness of catamorphisms obviates this problem and addresses it in a principled manner.…”

“…A follow-up work by Alexander et al [4] combined CTGGP with the scaffolding of Moraglio et al [24]. In essence, scaffolding mitigates infinite recursion by resorting to fitness cases whenever the argument of a recursive call is present among them.…”

Performance Optimization of Multi-Core Grammatical Evolution Generated Parallel Recursive Programs

“…The evolved programs exhibited a time complexity of O nlog(n) . Recently, Moraglio et al [10] used a nonrecursive scaffolding method to evolve recursive programs with a context free grammar based GP.…”

“…Then, we can refer the table for the repeated recursive calls, similar to Koza [9]. But this approach has often been criticized [10] in the EC community for not being an exact recursion.…”

Genetic Programming

“…Agapitos and Lucas [1,2] analysed the generality of evolving modular recursive sorting algorithms with the help of Object Oriented Genetic Programming (OOGP) by defining special classes and methods in Java. Moraglio et al, [10] presented a general non-recursive scaffolding method that evolved a recursive list reversal program using a context free grammar based GP.…”