The unconventional computing is a quest for new concepts, paradigms, architectures and implementations of computing devices that we were unaware before (as biochemical gates) or well forgotten (as analog computers). This Special Issue brings up reviews written by world leading experts in future and emergent computing. Topics discussed include mechanics of computation, analog computing, reversible machines, hyper-computation, intra-cellular synapses, enzymatic logical gates, microbial computing and Belousov-Zhabotinsky circuits.
Susan Stepney is a renowned expert in complexity, computation, physics and programming. In her paper, “Local and global models of physics and computation”, she shifts the meaning of computation onto a physical level and analyses a process of computation in terms of Newtonian and Lagrangian mechanics.
Bruce MacLennan is amongst father figures in emergent computation. In his paper, “The Promise of Analog Computation”, he demonstrates that analog computing operations are ubiquitous and unfolds a new perspective in future development of analog computers. He argues that “the contentious issue of the computational power of analog computers is addressed best on its own terms, rather by asking it within the context of Church-Turing computation, which distorts the relevant questions and their answers”.
Kenichi Morita is one of the world’s leading researchers in reversible and universal computation in cellular automata, grammars and Turing machines. His paper, “Reversibility in Space-Bounded Computation”, demonstrates the high computational potential of the reversible deterministic Turing machines by proving that these machines are capable for simulating irreversible deterministic and reversible non-deterministic Turing machines.
Mike Stannet is an expert in computation and space-time structures, hyper-computation, universality and automata. His paper, “Testing and Verification of Unconventional Computations using Generalised X-Machines”, discusses how X-machines, an automata-like generalized models of computation can be used as models of future and emergent computing devices. Stannet exemplifies applications of X-machines in cosmological hyper-computation and multiply accelerated membrane systems.
The research laboratory led by Evgeny Katz transforms unconventional computing from a purely theoretical field to a vibrant experimental area where concepts of unorthodox information processing and decision-making can be realized with biomolecules and, potentially, applied to personal illness treatment. In their paper, “Biochemical Flip-Flop Memory Systems – Essential Additions to Autonomous Biocomputing and Biosensing Systems”, Kevin MacVittie and Evgeny Katz show how memory systems can be integrated into biochemical information computing devices.
František Baluška and Stefano Mancuso are leaders in plant neurobiology and physiology, ethology of root plants and phytobionics. Their paper, “Synaptic View of Eukaryotic Cell”, expands a classical neuronal synaptic concept to intra-cellular synapses. Their paradigms could be used in the designs of future living computers and nanofactories of intra-cellular assembly of functional devices.
Andy Adamatzky and colleagues, in the paper, “On Logical Universality of Belousov-Zhabotinsky Vesicles”, show how logical gates can be implemented in ensembles of lipid vesicles filled with an excitable chemical system. The computation is implemented via collision of excitation wave fragments: by interpreting wave fragments as values of Boolean variables, Adamatzky et al. design collision-based illumination-controlled logical gates in Belousov-Zhabotinsky vesicles.
Martyn Amos’ research interests span computer science and biology; he works on computer architectures, agent-based simulation, computing dynamics and biological computing. His paper, “Population Based Microbial Computing”, shows how computing is implemented in bacterial colonies and outlines scientific and technological challenges of this approach.
This Special Issue on Unconventional Computing will help computer scientists, mathematicians, physicists, chemists, biologists and engineers to uncover many faces of computation and to inspire them to design their own theories of computation and prototypes of unconventional computing devices.
University of the West of England, Bristol, UK
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