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.

Evolving spiking networks with variable memristors (2011)
Presentation / Conference
Howard, G. D., Gale, E., Bull, L., de Lacy Costello, B., & Adamatzky, A. (2011, June). Evolving spiking networks with variable memristors. Paper presented at 13th annual conference on Genetic and evolutionary computation

Arithmetic dynamical genetic programming in the XCSF learning classifier system (2011)
Presentation / Conference
Preen, R., & Bull, L. (2011, June). Arithmetic dynamical genetic programming in the XCSF learning classifier system. Paper presented at IEEE Congress on Evolutionary Computation (CEC), 2011, New Orleans, US

This paper presents results from an investigation into using a continuous-valued dynamical system representation within the XCSF Learning Classifier System. In particular, dynamical arithmetic genetic networks are used to represent the traditional... Read More about Arithmetic dynamical genetic programming in the XCSF learning classifier system.

Towards imitation-enhanced reinforcement learning in multi-agent systems (2011)
Presentation / Conference
Erbas, M. D., Winfield, A. F., & Bull, L. (2011, April). Towards imitation-enhanced reinforcement learning in multi-agent systems. Paper presented at 2011 IEEE Symposium on Artificial Life (ALIFE)

Towards evolving spiking networks with memristive synapses (2011)
Presentation / Conference
Howard, G. D., Gale, E., Bull, L., de Lacy Costello, B., & Adamatzky, A. (2011, April). Towards evolving spiking networks with memristive synapses. Paper presented at IEEE Symposium on Artificial Life (ALIFE), 2011, Paris, France

This paper presents a spiking neuro-evolutionary system which implements memristors as neuromodulatory connections, ie whose weights can vary during a trial. The evolutionary design process exploits parameter self-adaptation and a constructionist app... Read More about Towards evolving spiking networks with memristive synapses.

Applications of Kauffman’s coevolutionary NKCS model to management and organization studies (2011)
Book Chapter
Vidgen, R., & Bull, L. (2011). Applications of Kauffman’s coevolutionary NKCS model to management and organization studies. In P. Allen, S. Maguire, & B. McKelvey (Eds.), The Sage Handbook of Complexity and Management (201-219). SAGE Publications Limited

A number of studies have used tuneable, abstract models of organism evolution like Kauffman's (1993) NK model to capture and explore aspects of organizations and their adaptation in the business environment (eg Levinthal, 1997; Rivkin, 2000; Lenox... Read More about Applications of Kauffman’s coevolutionary NKCS model to management and organization studies.

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.

A spiking neural representation for XCSF (2010)
Conference Proceeding
Lanzi, P. L., Howard, G., Howard, D., & Bull, L. (2010). A spiking neural representation for XCSF. . https://doi.org/10.1109/CEC.2010.5586035

This paper presents a Learning Classifier System (LCS) where each traditional rule is represented by a spiking neural network, a type of network with dynamic internal state. The evolutionary design process exploits parameter self-adaptation and a con... Read More about A spiking neural representation for XCSF.

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.

Imitation programming (2010)
Journal Article
Bull, L. (2010). Imitation programming. Lecture Notes in Artificial Intelligence, 6274 LNCS, 360-371. https://doi.org/10.1007/978-3-642-15323-5_31

Many nature-inspired mechanisms have been presented for computational design and optimization. This paper introduces a population-based approach inspired by a form of cultural learning - imitation. Imitation is typically defined as learning through t... Read More about Imitation programming.

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.

Parallel data mining-case study (2010)
Report
Tekiner, F., Pettipher, M., Bull, L., Studley, M., Whittley, I., & Bagnall, T. (2010). Parallel data mining-case study

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.