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Cartesian genetic programming for memristive logic circuits (2012)
Journal Article
Howard, G. D., Bull, L., & Adamatzky, A. (2012). Cartesian genetic programming for memristive logic circuits. Lecture Notes in Artificial Intelligence, 7244 LNCS, 37-48. https://doi.org/10.1007/978-3-642-29139-5_4

In this paper memristive logic circuits are evolved using Cartesian Genetic Programming. Graphs comprised of implication logic (IMP) nodes are compared to more ubiquitous NAND circuitry on a number of logic circuit problems and a robotic control task... Read More about Cartesian genetic programming for memristive logic circuits.

Using genetical and cultural search to design unorganised machines (2012)
Journal Article
Bull, L. (2012). Using genetical and cultural search to design unorganised machines. Evolutionary Intelligence, 5(1), 23-33. https://doi.org/10.1007/s12065-011-0061-4

In 1948 Turing presented a general representation scheme by which to achieve artificial intelligence-his unorganised machines. Significantly, these were a form of discrete dynamical system and yet dynamical representations remain almost unexplored wi... Read More about Using genetical and cultural search to design unorganised machines.

On natural genetic engineering: structural dynamism in random boolean networks (2012)
Journal Article
Bull, L. (2012). On natural genetic engineering: structural dynamism in random boolean networks

This short paper presents an abstract, tunable model of genomic structural change within the cell lifecycle and explores its use with simulated evolution. A well-known Boolean model of genetic regulatory networks is extended to include changes in nod... Read More about On natural genetic engineering: structural dynamism in random boolean networks.

Evolving boolean networks with structural dynamism (2012)
Journal Article
Bull, L. (2012). Evolving boolean networks with structural dynamism. Artificial Life, 18(4), 385-397. https://doi.org/10.1162/ARTL_a_00073

This short article presents an abstract, tunable model of genomic structural change within the cell life cycle and explores its use with simulated evolution. A well-known Boolean model of genetic regulatory networks is extended to include changes in... Read More about Evolving boolean networks with structural dynamism.

A simple computational cell: Coupling boolean gene and protein networks (2012)
Journal Article
Bull, L. (2012). A simple computational cell: Coupling boolean gene and protein networks. Artificial Life, 18(2), 223-236

This article presents an abstract, tunable model containing two of the principal information-processing features of cells and explores its use with simulated evolution. The random Boolean model of genetic regulatory networks is extended to include a... Read More about A simple computational cell: Coupling boolean gene and protein networks.

Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks (2011)
Journal Article
Holley, J., Jahan, I., De Lacy Costello, B., Bull, L., & Adamatzky, A. (2011). Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks. Physical Review E, 84(5), 056110. https://doi.org/10.1103/PhysRevE.84.056110

Excitation waves on a subexcitable Belousov-Zhabotinsky (BZ) substrate can be manipulated by chemical variations in the substrate and by interactions with other waves. Symbolic assignment and interpretation of wave dynamics can be used to perform log... Read More about Logical and arithmetic circuits in Belousov-Zhabotinsky encapsulated disks.

On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium (2011)
Journal Article
Adamatzky, A., Holley, J., Bull, L., & De Lacy Costello, B. (2011). On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium. Chaos, Solitons and Fractals, 44(10), 779-790. https://doi.org/10.1016/j.chaos.2011.03.010

We introduce results of computer experiments on information processing in a hexagonal array of vesicles filled with Belousov-Zhabotinsky (BZ) solution in a sub-excitable mode. We represent values of Boolean variables by excitation wave-fragments and... Read More about On computing in fine-grained compartmentalised Belousov-Zhabotinsky medium.

Towards a mapping of modern AIS and LCS (2011)
Journal Article
Bull, L. (2011). Towards a mapping of modern AIS and LCS. Lecture Notes in Artificial Intelligence, 6825 LNCS, 371-382. https://doi.org/10.1007/978-3-642-22371-6_32

For many years correlations between aspects of Artificial Immune Systems (AIS) and Learning Classifier Systems (LCS) have been highlighted. However, neither field appears to have benefitted from such work not least since the differences between the t... Read More about Towards a mapping of modern AIS and LCS.

Vesicle computers: Approximating a Voronoi diagram using Voronoi automata (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., Holley, J., Gorecki, J., & Bull, L. (2011). Vesicle computers: Approximating a Voronoi diagram using Voronoi automata. Chaos, Solitons and Fractals, 44(7), 480-489. https://doi.org/10.1016/j.chaos.2011.01.016

Irregular arrangements of vesicles filled with excitable and precipitating chemical systems are imitated by Voronoi automata - finite-state machines defined on a planar Voronoi diagram. Every Voronoi cell takes four states: resting, excited, refracto... Read More about Vesicle computers: Approximating a Voronoi diagram using Voronoi automata.

Computational modalities of Belousov-Zhabotinsky encapsulated vesicles (2011)
Journal Article
Holley, J., Adamatzky, A., Bull, L., De Lacy Costello, B., & Jahan, I. (2011). Computational modalities of Belousov-Zhabotinsky encapsulated vesicles. Nano Communication Networks, 2(1), 50-61. https://doi.org/10.1016/j.nancom.2011.02.002

We present both simulated and partial empirical evidences for the computational utility of many connected vesicle analogues of an encapsulated nonlinear chemical processing medium. By connecting small vesicles containing a solution of sub-excitable B... Read More about Computational modalities of Belousov-Zhabotinsky encapsulated vesicles.

Towards arithmetic circuits in sub-excitable chemical media (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., Bull, L., & Holley, J. (2011). Towards arithmetic circuits in sub-excitable chemical media. Israel Journal of Chemistry, 51(1), 56-66. https://doi.org/10.1002/ijch.201000046

A sub-excitable Belousov-Zhabotinsky medium exhibits localized travelling excitations (in contrast to an excitable medium exhibiting target or spiral waves). Initially assymetric perturbations give birth to excitation wave-fragments. The shape and ve... Read More about Towards arithmetic circuits in sub-excitable chemical media.

On polymorphic logical gates in subexcitable chemical medium (2011)
Journal Article
Adamatzky, A., De Lacy Costello, B., & Bull, L. (2011). On polymorphic logical gates in subexcitable chemical medium. International Journal of Bifurcation and Chaos, 21(07), 1977-1986. https://doi.org/10.1142/S0218127411029574

In a subexcitable light-sensitive Belousov-Zhabotinsky (BZ) chemical medium an asymmetric disturbance causes the formation of localized traveling wave-fragments. Under the right conditions these wave-fragments can conserve their shape and velocity ve... Read More about On polymorphic logical gates in subexcitable chemical medium.

Artificial symbiogenesis and differing reproduction rates (2010)
Journal Article
Bull, L. (2010). Artificial symbiogenesis and differing reproduction rates. Artificial Life, 16(1), 65-72. https://doi.org/10.1162/artl.2009.16.1.16102

Symbiosis is the phenomenon in which organisms of different species live together in close association. Symbiogenesis is the name given to the process by which symbiotic partners combine and unify. This letter reconsiders previous work using the NKCS... Read More about Artificial symbiogenesis and differing reproduction rates.

Use of a connection-selection scheme in neural XCSF (2010)
Journal Article
Howard, G. D., Bull, L., & Lanzi, P. L. (2010). Use of a connection-selection scheme in neural XCSF. Lecture Notes in Artificial Intelligence, 6471 LNAI, 87-106. https://doi.org/10.1007/978-3-642-17508-4_7

XCSF is a modern form of Learning Classifier System (LCS) that has proven successful in a number of problem domains. In this paper we exploit the modular nature of XCSF to include a number of extensions, namely a neural classifier representation, sel... Read More about Use of a connection-selection scheme in neural XCSF.

Stochastic automated search methods in cellular automata: The discovery of tens of thousands of glider guns (2010)
Journal Article
Sapin, E., Adamatzky, A., Collet, P., & Bull, L. (2010). Stochastic automated search methods in cellular automata: The discovery of tens of thousands of glider guns. Natural Computing, 9(3), 513-543. https://doi.org/10.1007/s11047-009-9109-0

This paper deals with the spontaneous emergence of glider guns in cellular automata. An evolutionary search for glider guns with different parameters is described and other search techniques are also presented to provide a benchmark. We demonstrate t... Read More about Stochastic automated search methods in cellular automata: The discovery of tens of thousands of glider guns.

Index permutations and classes of additive cellular automata rules with isomorphic STD (2010)
Journal Article
Bulitko, V., Voorhees, B., Alonso-Sanz, R., Bull, L., Anghelescu, P., Ionita, S., …Jin, W. (2010). Index permutations and classes of additive cellular automata rules with isomorphic STD. Journal of Cellular Automata, 5(1-2), 1-28

First we consider the question of identifying linear transformations that transform any additive CA rule into an additive CA rule with an isomorphic STD. A general condition is derived. Following on this, we consider a subclass of such transformation... Read More about Index permutations and classes of additive cellular automata rules with isomorphic STD.

On dynamical genetic programming: Simple Boolean networks in learning classifier systems (2009)
Journal Article
Bull, L. (2009). On dynamical genetic programming: Simple Boolean networks in learning classifier systems. International Journal of Parallel, Emergent and Distributed Systems, 24(5), 421-442. https://doi.org/10.1080/17445760802660387

Many representations have been presented to enable the effective evolution of computer programs. Turing was perhaps the first to present a general scheme by which to achieve this end. Significantly, Turing proposed a form of discrete dynamical system... Read More about On dynamical genetic programming: Simple Boolean networks in learning classifier systems.

Genetic approaches to search for computing patterns in cellular automata (2009)
Journal Article
Sapin, E., Bull, L., & Adamatzky, A. (2009). Genetic approaches to search for computing patterns in cellular automata. IEEE Computational Intelligence Magazine, 4(3), 20-28. https://doi.org/10.1109/MCI.2009.933097

The emergence of collision based computing in complex systems with local interactions is discussed. Simulations of logic gates have been inspired by the simulation of an AND gate by the Game of Life. The evolutionary algorithm is also used to modify... Read More about Genetic approaches to search for computing patterns in cellular automata.

Computer music meets unconventional computing: Towards sound synthesis with in vitro neuronal networks (2009)
Journal Article
Miranda, E. R., Bull, L., Gueguen, F., & Uroukov, I. S. (2009). Computer music meets unconventional computing: Towards sound synthesis with in vitro neuronal networks. Computer Music Journal, 33(1), 9-18. https://doi.org/10.1162/comj.2009.33.1.9

The feasibility of synthesizing sounds with hybrid wetware-silicon devices has been explored with the use of in vitro neuronal networks. The basics of culturing brain cells has been introduced while the procedures that has been established to stimula... Read More about Computer music meets unconventional computing: Towards sound synthesis with in vitro neuronal networks.