abstract = "This paper describes Christiansen grammar evolution
(CGE), a new evolutionary automatic programming
algorithm that extends standard grammar evolution (GE)
by replacing context-free grammars by Christiansen
grammars. GE only takes into account syntactic
restrictions to generate valid individuals. CGE adds
semantics to ensure that both semantically and
syntactically valid individuals are generated. It is
empirically shown that our approach improves GE
performance and even allows the solution of some
problems are difficult to tackle by GE",
notes = "Uses GE but non-BNF grammar, instead grammar is
dynamic. Claims only syntactic and _semantically_
correct programs are generated. Backtracking. Position
independence. Cites \cite{oneill:2004:gew:mone}.