abstract = "Previous work described a way to evolutionarily select
the architecture of a multi-part computer program From
among preexisting alternatives in the population while
concurrently solving a problem during a run of genetic
programming. This report describes six new
architecture-altering operations that provide a way to
evolve the architecture of a multi-part program in the
sense of actually changing the architecture of programs
dynamically during the run. The new
architecture-altering operations are motivated by the
naturally occurring operation of gene duplication as
described in Susumu Ohno's provocative 1970 book
Evolution by Means of Gene Duplication as well as the
naturally occurring operation of gene deletion. The six
new architecture-altering operations are branch
duplication, argument duplication, branch creation,
argument creation, branch deletion and argument
deletion. A connection is made between genetic
programming and other techniques of automated problem
solving by interpreting the architecture-altering
operations as providing an automated way to specialize
and generalize programs. The report demonstrates that a
hierarchical architecture can be evolved to solve an
illustrative symbolic regression problem using the
architecture- altering operations. Future work will
study the amount of additional computational effort
required to employ the architecture-altering
operations.",