Road map
HAL is currently near the beginning of its lifespan. Hopefully it will
see some extensive development and fully realise its potential.
Some of the things that need doing include:
- Create some selection criteria which modify patterns on the sides of the
organisms to better illustrate the potential for evolving circuitry.
- Produce implementations of the model on progressively more appropriate
hardware. Initially this will mean using patterns in the calculation layer
to specify an external phenotype which can be implemented very simply and
rapidly in programmable logic.
- Rework the model so all offspring have the same orientation (rather than
being pointing in four possible directions). This would removes the
restriction on the calculation layers that they be rotationally symmetric
and simplify the growth of cells.
- HAL's long-term viability as a method of solving optimisation problems
depends crucially on our ability to develop sexual organisms, or those that
exhibit significant crossover frequency.
Lack of sex appears to be a fundamental stumbling block which currently
prevents artificial life models from competing properly with more
conventional genetic algorithms which employ externally imposed sex.
We plan to create an environment where sex evolves naturally from asexual
organisms. This will involve creating a number of other models, mainly of
parasitism and gene repair, to investigate what dynamics are most likely to
lead to the desired outcome, and then finding methods of creating a
suitable environment for the evolution of sex within our main model.
With regards to the optimisation problems we plan to use, in order:
- The ability to solve simple arithmetic and logical problems.
- The ability to use memory. We plan to present organisms with a series
of numbers and then return them at a later date, on request.
- The ability to form multi-cellular organisms. We plan to drive
organisms into this by selecting for small organism size in addition to
presenting particular organisms with harder memory problems than any
individual can handle in the hope that they will delegate parts of this to
their sisters.
- The ability to play strategic games. See the details of HAL's driving
problem for more details about this.
The point behind using a set of problems connected with memorising sequences
of numbers is that we don't believe in rewarding organisms in our model who
perform in a pleasing manner directly with reproductive success, rather we
prefer to pay them for their services, and then charge them for
reproductive facilities at a later date.
There are essentially two main methods of implementing such a scheme, one
involves offering the organisms a precious material, or scarce vitamin,
essential to reproduction in payment for their services. The other is
to pay organisms for their services in e-money and then extract payments
from them when they attempt to reproduce. We have chosen the second
alternative over the first on the grounds that it simplifies our model.
Paying organisms with e-money allows them more choose concerning when they
reproduce, provides a medium of exchange for trade within the model and
encourages parasites within the model. Parasites are important for the
evolution of sex. The positive effects they have in this area and in terms
of driving the model away from local minima by continuously deforming the
fitness landscape more than offset the problems that they cause in terms
of causing organisms to "waste" resources fighting them and when finding
a 'model' organism who is healthy at the end of a run.