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Russell K. Standish

Publications and source records attributed to Russell K. Standish.

At least 37 records · Page 2Linked to original sources
arXiv2005

The importance of the observer in science

The concept of {\em complexity} (as a quantity) has been plagued by numerous contradictory and confusing definitions. By explicitly recognising a role for the observer of a system, an observer that attaches meaning to data about the system, these contradictions can be resolved, and the numerous complexity measures that have been proposed can be seen as cases where different observers are relevant, and/or being proxy measures that loosely scale with complexity, but are easy to compute from the available data. Much of the epistemic confusion in the subject can be squarely placed at science's tradition of removing the observer from the description in order to guarantee {\em objectivity}. Explicitly acknowledging the role of the observer helps untangle other confused subject areas. {\em Emergence} is a topic about which much ink has been spilt, but it can be understand easily as an irreducibility between description space and meaning space. Quantum Mechanics can also be understood as a theory of observation. The success in explaining quantum mechanics, leads one to conjecture that all of physics may be reducible to properties of the observer. And indeed, what are the necessary (as opposed to contingent) properties of an observer? This requires a full theory of consciousness, from which we are a long way from obtaining. However where progress does appear to have been made, e.g. Daniel Dennett's {\em Consciousness Explained}, a recurring theme of self-observation is a crucial ingredient.

physics.pop-ph↗
arXiv2005

Complexity of Networks

Network or graph structures are ubiquitous in the study of complex systems. Often, we are interested in complexity trends of these system as it evolves under some dynamic. An example might be looking at the complexity of a food web as species enter an ecosystem via migration or speciation, and leave via extinction. In this paper, a complexity measure of networks is proposed based on the {\em complexity is information content} paradigm. To apply this paradigm to any object, one must fix two things: a representation language, in which strings of symbols from some alphabet describe, or stand for the objects being considered; and a means of determining when two such descriptions refer to the same object. With these two things set, the information content of an object can be computed in principle from the number of equivalent descriptions describing a particular object. I propose a simple representation language for undirected graphs that can be encoded as a bitstring, and equivalence is a topological equivalence. I also present an algorithm for computing the complexity of an arbitrary undirected network.

cs.IT↗
arXiv2004

Emergent Effective Collusion in an Economy of Perfectly Rational Competitors

We consider a simple model of rational agents competing in a single product market described by simple linear demand curve. Contrary to accepted economic theory, the agents' production levels synchronise in the absence of conscious collusion, leading to a downward spiraling of market total production until the monopoly price level is realised. This is in stark contrast to the standard predictions of an ideal rational competitive market. Some form of randomness in the form of agent irrationality, or non-synchronous updates is needed to break this emergent "collusion"

nlin.AO↗
arXiv2004

Ecolab, Webworld and self-organisation

Ecolab and Webworld are both models of evolution produced by adding evolution to ecological equations. They differ primarily in the form of the ecological equations. Both models are self-organised to a state where extinctions balance speciations. However, Ecolab shows evidence of this self-organised state being critical, whereas Webworld does not. This paper examines the self-organised states of these two models and suggest the likely cause of the difference. Also the lifetime distribution for a mean field version of Ecolab is computed, showing that the fat tail of the distribution is due to coevolutionary adaption of the species.

nlin.AO↗
arXiv2004

Tierra's missing neutrality: case solved

The concept of neutral evolutionary networks being a significant factor in evolutionary dynamics was first proposed by Huynen {\em et al.} about 7 years ago. In one sense, the principle is easy to state -- because most mutations to an organism are deleterious, one would expect that neutral mutations that don't affect the phenotype will have disproportionately greater representation amongst successor organisms than one would expect if each mutation was equally likely. So it was with great surprise that I noted neutral mutations being very rare in a visualisation of phylogenetic trees generated in {\em Tierra}, since I already knew that there was a significant amount of neutrality in the Tierra genotype-phenotype map. It turns out that competition for resources between host and parasite inhibits neutral evolution.

nlin.AO↗
arXiv2004

Why Occam's Razor

Ensemble theories have received a lot of interest recently as a means of explaining a lot of the detailed complexity observed in reality by a vastly simpler description ``every possibility exists'' and a selection principle ({\em Anthropic Principle}) ``we only observe that which is consistent with our existence''. In this paper I show why, in an ensemble theory of the universe, we should be inhabiting one of the elements of that ensemble with least information content that satisfies the anthropic principle. This explains the effectiveness of aesthetic principles such as Occam's razor in predicting usefulness of scientific theories. I also show, with a couple of reasonable assumptions about the phenomenon of consciousness, the linear structure of quantum mechanics can be derived.

physics.gen-ph↗
arXiv2004

A system for reflection in C++

Object-oriented programming languages such as Java and Objective C have become popular for implementing agent-based and other object-based simulations since objects in those languages can {\em reflect} (i.e. make runtime queries of an object's structure). This allows, for example, a fairly trivial {\em serialisation} routine (conversion of an object into a binary representation that can be stored or passed over a network) to be written. However C++ does not offer this ability, as type information is thrown away at compile time. Yet C++ is often a preferred development environment, whether for performance reasons or for its expressive features such as operator overloading. In this paper, we present the {\em Classdesc} system which brings many of the benefits of object reflection to C++.

cs.PL↗
arXiv2004

Running C++ models undet the Swarm environment

Objective-C is still the language of choice if users want to run their simulation efficiently under the Swarm environment since the Swarm environment itself was written in Objective-C. The language is a fast, object-oriented and easy to learn. However, the language is less well known than, less expressive than, and lacks support for many important features of C++ (eg. OpenMP for high performance computing application). In this paper, we present a methodology and software tools that we have developed for auto generating an Objective-C object template (and all the necessary interfacing functions) from a given C++ model, utilising the Classdesc's object description technology, so that the C++ model can both be run and accessed under the Objective-C and C++ environments. We also present a methodology for modifying an existing Swarm application to make part of the model (eg. the heatbug's step method) run under the C++ environment.

cs.MA↗
arXiv2004

EcoLab: Agent Based Modeling for C++ programmers

\EcoLab{} is an agent based modeling system for C++ programmers, strongly influenced by the design of Swarm. This paper is just a brief outline of \EcoLab's features, more details can be found in other published articles, documentation and source code from the \EcoLab{} website.

cs.MA↗
arXiv2004

ClassdescMP: Easy MPI programming in C++

ClassdescMP is a distributed memory parallel programming system for use with C++ and MPI. It uses the Classdesc reflection system to ease the task of building complicated messages to be sent between processes. It doesn't hide the underlying MPI API, so it is an augmentation of MPI capabilities. Users can still call standard MPI function calls if needed for performance reasons.

cs.DC↗
arXiv2004

The case of the missing neutrality

The concept of neutral evolutionary networks being a significant factor in evolutionary dynamics was first proposed by Huynen {\em et al.} about 7 years ago. In one sense, the principle is easy to state -- because most mutations to an organism are deleterious, one would expect that neutral mutations that don't affect the phenotype will have disproportionately greater representation amongst successor organisms than one would expect if each mutation was equally likely. So it was with great surprise that I noted neutral mutations being very rare in a visualisation of phylogenetic trees generated in {\em Tierra}, since I already knew that there was a significant amount of neutrality in the Tierra genotype-phenotype map. The paper reports on an investigation into this mystery.

nlin.AO↗
arXiv2002

Diversity Evolution

Bedau has developed a general set of evolutionary statistics that quantify the adaptive component of evolutionary processes. On the basis of these measures, he has proposed a set of 4 classes of evolutionary system. All artificial life sytems so far looked at fall into the first 3 classes, whereas the biosphere, and possibly the human economy belongs to the 4th class. The challenge to the artificial life community is to identify exactly what is difference between these natural evolutionary systems, and existing artificial life systems. At ALife VII, I presented a study using an artificial evolutionary ecology called \EcoLab. Bedau's statistics captured the qualitative behaviour of the model. \EcoLab{} exhibited behaviour from the first 3 classes, but not class 4, which is characterised by unbounded growth in diversity. \EcoLab{} exhibits a critical surface given by an inverse relationship between connectivity and diversity, above which the model cannot tarry long. Thus in order to get unbounded diversity increase, there needs to be a corresponding connectivity reducing (or food web pruning) process. This paper reexamines this question in light of two possible processes that reduce ecosystem connectivity: a tendency for specialisation and increase in biogeographic zones through continental drift.

nlin.AO↗
arXiv2002

Open-Ended Artificial Evolution

Of all the issues discussed at {\em Alife VII: Looking Forward, Looking Backward}, the issue of whether it was possible to create an artificial life system that exhibits {\em open-ended evolution} of novelty is by far the biggest. Of the 14 open problems settled on as a result of debate at the conference, some 6 are directly, or indirectly related to this issue. Most people equate open-ended evolution with complexity growth, although a priori these seem to be different things. In this paper I report on experiments to measure the complexity of Tierran organisms, and show the results for a {\em size-neutral} run of Tierra. In this run, no increase in organismal complexity was observed, although organism size did increase through the run. This result is discussed, offering some signposts on path to solving the issue of open ended evolution.

nlin.AO↗
arXiv2001

On Complexity and Emergence

Numerous definitions for complexity have been proposed over the last half century, with little consensus achieved on how to use the term. A definition of complexity is supplied here that is closely related to the Kolmogorov Complexity and Shannon Entropy measures widely used as complexity measures, yet addresses a number of concerns raised against these measures. However, the price of doing this is to introduce context dependence into the definition of complexity. It is argued that such context dependence is an inherent property of complexity, and related concepts such as entropy and emergence. Scientists are uncomfortable with such context dependence, which smacks of subjectivity, and this is perhaps the reason why little agreement has been found on the meaning of these terms.

nlin.AO↗
arXiv2000

Evolution in the Multiverse

In the {\em Many Worlds Interpretation} of quantum mechanics, the range of possible worlds (or histories) provides variation, and the Anthropic Principle is a selective principle analogous to natural selection. When looked on in this way, the ``process'' by which the laws and constants of physics is determined not too different from the process that gave rise to our current biodiversity, i.e. Darwinian evolution. This has implications for the fields of SETI and Artificial Life, which are based on a philosophy of the inevitability of life.

physics.gen-ph↗
arXiv2000

An Ecolab Perspective on the Bedau Evolutionary Statistics

At Alife VI, Mark Bedau proposed some evolutionary statistics as a means of classifying different evolutionary systems. Ecolab, whilst not an artificial life system, is a model of an evolving ecology that has advantages of mathematical tractability and computational simplicity. The Bedau statistics are well defined for Ecolab, and this paper reports statistics measured for typical Ecolab runs, as a function of mutation rate. The behaviour ranges from class 1 (when mutation is switched off), through class 3 at intermediate mutation rates (corresponding to scale free dynamics) to class 2 at high mutation rates. The class 3/class 2 transition corresponds to an error threshold. Class 4 behaviour, which is typified by the Biosphere, is characterised by unbounded growth in diversity. It turns out that Ecolab is governed by an inverse relationship between diversity and connectivity, which also seems likely of the Biosphere. In Ecolab, the mutation operator is conservative with respect to connectivity, which explains the boundedness of diversity. The only way to get class 4 behaviour in Ecolab is to develop an evolutionary dynamics that reduces connectivity of time.

nlin.AO↗
arXiv2000

Some Techniques for the Measurement of Complexity in Tierra

Recently, Adami and coworkers have been able to measure the information content of digital organisms living in their {\em Avida} artificial life system. They show that over time, the organisms behave like Maxwell's demon, accreting information (or complexity) as they evolve. In {\em Avida} the organisms don't interact with each other, merely reproduce at a particular rate (their fitness), and attempt to evaluate an externally given arithmetic function in order win bonus fitness points. Measuring the information content of a digital organism is essentially a process of counting the number of genotypes that give rise to the same phenotype. Whilst Avidan organisms have a particularly simple phenotype, Tierran organisms interact with each other, giving rise to an ecology of phenotypes. In this paper, I discuss techniques for comparing pairs of Tierran organisms to determine if they are phenotypically equivalent. I then discuss a method for computing an estimate of the number of phenotypically equivalent genotypes that is more accurate than the ``hot site'' estimate used by Adami's group. Finally, I report on an experimental analysis of a Tierra run.

nlin.AO↗