It is Time for New Perspectives on How to Fight Bloat in GP

The present and future of evolutionary algorithms depends on the proper use of modern parallel and distributed computing infrastructures. Although still sequential approaches dominate the landscape, available multi-core, many-core and distributed systems will make users and researchers to more frequently deploy parallel version of the algorithms. In such a scenario, new possibilities arise regarding the time saved when parallel evaluation of individuals are performed. And this time saving is particularly relevant in Genetic Programming. This paper studies how evaluation time influences not only time to solution in parallel/distributed systems, but may also affect size evolution of individuals in the population, and eventually will reduce the bloat phenomenon GP features. This paper considers time and space as two sides of a single coin when devising a more natural method for fighting bloat. This new perspective allows us to understand that new methods for bloat control can be derived, and the first of such a method is described and tested. Experimental data confirms the strength of the approach: using computing time as a measure of individuals' complexity allows to control the growth in size of genetic programming individuals

Universal Consistency and Bloat in GP

In this paper, we provide an analysis of Genetic Programming (GP) from the Statistical Learning Theory viewpoint in the scope of symbolic regression. Firstly, we are interested in Universal Consistency, i.e. the fact that the solution minimizing the empirical error does converge to the best possible error when the number of examples goes to infinity, and secondly, we focus our attention on the uncontrolled growth of program length (i.e. bloat), which is a well-known problem in GP. Results show that (1) several kinds of code bloats may be identified and that (2) Universal consistency can be obtained as well as avoiding bloat under some con- ditions. We conclude by describing an ad hoc method that makes it possible simultaneously to avoid bloat and to ensure universal consistency

Apprentissage statistique et programmation génétique: la croissance du code est-elle inévitable ?

Universal Consistency, the convergence to the minimum possible error rate in learning through genetic programming (GP), and Code bloat, the excessive increase of code size, are important issues in GP. This paper proposes a theoretical analysis of universal consistency and code bloat in the framework of symbolic regression in GP, from the viewpoint of Statistical Learning Theory, a well grounded mathematical toolbox for Machine Learning. Two kinds of bloat must be distinguished in that context, depending whether the target function has finite description length or not. Then, the Vapnik-Chervonenkis dimension of programs is computed, and we prove that a parsimonious fitness ensures Universal Consistency (i.e. the fact that the solution minimizing the empirical error does converge to the best possible error when the number of examples goes to infinity). However, it is proved that the standard method consisting in choosing a maximal program size depending on the number of examples might still result in programs of infinitely increasing size with their accuracy; a fitness biased by parsimony pressure is proposed. This fitness avoids unnecessary bloat while nevertheless preserving the Universal Consistency

Automatic design of analogue circuits

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Evolvable Hardware (EHW) is a promising area in electronics today. Evolutionary Algorithms (EA), together with a circuit simulation tool or real hardware, automatically designs a circuit for a given problem. The circuits evolved may have unconventional designs and be less dependent on the personal knowledge of a designer. Nowadays, EA are represented by Genetic Algorithms (GA), Genetic Programming (GP) and Evolutionary Strategy (ES). While GA is definitely the most popular tool, GP has rapidly developed in recent years and is notable by its outstanding results. However, to date the use of ES for analogue circuit synthesis has been limited to a few applications. This work is devoted to exploring the potential of ES to create novel analogue designs. The narrative of the thesis starts with a framework of an ES-based system generating simple circuits, such as low pass filters. Then it continues with a step-by-step progression to increasingly sophisticated designs that require additional strength from the system. Finally, it describes the modernization of the system using novel techniques that enable the synthesis of complex multi-pin circuits that are newly evolved. It has been discovered that ES has strong power to synthesize analogue circuits. The circuits evolved in the first part of the thesis exceed similar results made previously using other techniques in a component economy, in the better functioning of the evolved circuits and in the computing power spent to reach the results. The target circuits for evolution in the second half are chosen by the author to challenge the capability of the developed system. By functioning, they do not belong to the conventional analogue domain but to applications that are usually adopted by digital circuits. To solve the design tasks, the system has been gradually developed to support the ability of evolving increasingly complex circuits. As a final result, a state-of-the-art ES-based system has been developed that possesses a novel mutation paradigm, with an ability to create, store and reuse substructures, to adapt the mutation, selection parameters and population size, utilize automatic incremental evolution and use the power of parallel computing. It has been discovered that with the ability to synthesis the most up-to-date multi-pin complex analogue circuits that have ever been automatically synthesized before, the system is capable of synthesizing circuits that are problematic for conventional design with application domains that lay beyond the conventional application domain for analogue circuits

Degradation of crude protein and starch of corn and wheat grains in the rumen

The major objectives of the present thesis were to characterize the ruminal crude protein (CP) and starch degradation of different genotypes of corn and wheat grains and to predict the effective degradation (ED) of CP and starch with easily measurable characteristics. The in situ method is the standard technique to study the ruminal degradation of feeds in many feed evaluation systems. This technique was originally applied to study forages and it was therefore necessary to clarify methodical details related to the measurements of in situ starch degradation from cereal grains. Two in vitro and one in situ approach were conducted to study the loss of secondary starch particles from bags with different pore sizes used for the in situ incubation of different cereal grains. In the first in vitro study ground wheat was incubated in bags (pore size: 50 µm) over different time spans in a modified rumen simulation technique. Bag residues and fermenter fluids were analyzed for their starch content. In the second in vitro study ground wheat, barley, and corn were incubated with bags of pore sizes of 50, 30 (except corn), 20, and 6 µm. In the in situ study ground wheat, barley, corn, and oats were rumen incubated over different time spans using bags with pore sizes of 50, 20, and 6 µm. The starch content of the grains and bag residues was analyzed enzymatically and the degradation characteristics of starch were calculated for each grain type and pore size. It was shown for the first time that incubating wheat and barley in bags with 50 and 30 µm pore size lead to a substantial amount of secondary starch particle losses during incubation process in vitro. These losses were not detectable when the grains were incubated with bags having pore sizes of 20 and 6 µm. Independent of the bags pore size no secondary starch particle losses were found by the incubation of corn. Thus corn can be studied in situ even with bags with 50 µm pore size. Oats showed very high washout losses with all pore sizes tested in the present thesis and therefore none of them is suitable to study the starch degradation measurements of oats. Because of methodical problems of gas accumulation in bags having pore sizes < 50 µm, no recommendations can be provided for the in situ evaluation of wheat and barley. Further research is necessary to solve these problems. In the second and third study of the present thesis ruminal in situ degradation of 20 corn grain genotypes and 20 wheat grain genotypes was measured in three lactating Jersey cows. In both experiments the same techniques were used to characterize the ruminal degradation of CP and starch. Ground grains (2 mm) were rumen incubated in bags (50 µm pore size) over different time spans. Grains and bag residues were analyzed for their CP and starch content. The degradation parameters and the ED were calculated for dry matter (DM), CP, and starch. Gas production (GP) of ground grains (1 mm) was recorded after incubation over different time spans in buffered ruminal fluid and fitted to an exponential equation to determine GP parameters. To predict ED of CP and starch correlations with physical and chemical characteristics and in vitro measurements were evaluated and stepwise multiple linear regression analyses were applied. The in situ parameters (soluble fraction, potential degradable fraction, and degradation rate) varied widely between genotypes of corn and wheat grains. The ED of DM, CP, and starch showed a high variation for corn grain genotypes. Due to the high degradation rates, the ED of wheat grains were similar between genotypes. The GP rate was in good agreement with the in situ values for corn grains, whereas no systematic relationship between both methods was observed for wheat grains. Evaluation of correlation analysis showed significant relationships between calculated ED of CP and several amino acids (AA) for both grain types. This indicates that the protein composition of the grains influences CP degradation in the rumen. Similar relationships were found between the same AA and ED of starch of corn grains which highlights the impact of the protein composition on ruminal starch degradation for this grain type. For both grain types, the ED of starch and CP could be predicted accurately from physical and chemical characteristics alone or in combination with GP measurements. Thus, the equations presented in the present thesis can be used to obtain rapid and cost effective information on ruminal degradation of CP and starch for corn and wheat grains. The results of the present thesis show that there is considerable variation of ruminal CP and starch degradation from different genotypes of corn and also albeit to a lesser extent for wheat grains. Differences in ED of starch should be taken into account when formulating rations containing significant amounts of corn and wheat grains. In the case of corn grains differences in ED of CP should also be accounted for.Die Hauptziele der vorliegenden Arbeit waren es, den Rohprotein (XP) und Stärkeabbau unterschiedlicher Genotypen von Mais- und Weizenkörnern im Pansen zu charakterisieren und den effektiven Abbau (ED) des XP und der Stärke mit einfach messbaren Parametern zu schätzen. Die in situ Methode ist in vielen Futterbewertungssystemen die Standard-Methode um den ruminalen Abbau von Futtermitteln zu untersuchen. Diese Methode wurde ursprünglich für Grobfuttermittel angewendet und es war daher notwendig methodische Details der in situ Methode genauer zu untersuchen. Um sekundäre Stärkepartikelverluste bei der in situ Inkubation verschiedener Getreidearten zu untersuchen, wurden zwei in vitro und eine in situ Untersuchung durchgeführt. Bei den in vitro Untersuchungen wurden Weizen, Gerste und Maiskörner mit Beuteln einer Porengröße von 50, 30 (außer Mais), 20 und 6 µm in einem modifizierten Pansensimulationssystem inkubiert. Die Beutelrückstände und Fermenterflüssigkeiten wurden anschließend auf ihren Stärkegehalt hin untersucht. Bei der in situ Untersuchung wurden Weizen, Gerste, Mais und Haferkörner über verschiedene Zeitspannen in Beuteln mit einer Porengröße von 50, 20 und 6 µm im Pansen inkubiert. Der Stärkegehalt der Getreide und Beutelrückstände wurde ermittelt und die Abbaucharakteristik der Stärke für jede Getreideart und Porengröße angepasst. Es konnte zum ersten Mal gezeigt werden, dass es bei der Inkubation von Weizen und Gerste in Beuteln mit einer Porengröße von 50 und 30 µm zu einer bedeutenden Menge an sekundären Stärkepartikelverlusten im in vitro Inkubationsverlauf kommt. Diese Verluste waren nicht nachweisbar bei Porengrößen von 20 und 6 µm. Es konnten keine sekundären Stärkepartikelverluste bei der Inkubation von Mais festgestellt werden, daher können für in situ Untersuchungen von Mais auch Beutel mit einer Porengröße von 50 µm verwendet werden. Bei Hafer wurden bei allen getesteten Porengrößen sehr hohe Waschverluste festgestellt, weshalb keine von diesen Porengrößen zur Untersuchung des Stärkeabbaus von Hafer empfohlen werden kann. Aufgrund der Akkumulation von Gas in Beuteln mit einer Porengröße < 50 µm, können keine Empfehlungen hinsichtlich der in situ Untersuchung von Weizen und Gerste gegeben werden. Zur Lösung dieses Problems sind weitere Untersuchungen notwendig. In der zweiten und dritten Studie der vorliegenden Arbeit wurde der in situ Abbau von je 20 Genotypen von Mais und Weizen im Pansen untersucht. In beiden Untersuchungen wurden die gleichen Techniken angewendet um den XP- und Stärkeabbau zu charakterisieren. Die gemahlenen Körner (2 mm) wurden in Beuteln (Porengröße: 50 µm) über verschiedene Zeitspannen im Pansen inkubiert. Die Getreide und Beutelrückstände wurden auf ihren XP- und Stärkegehalt untersucht. Anschließend wurden die Abbauparameter und der ED für die Trockenmasse (TM), das XP und die Stärke berechnet. Die Gasbildung (GB) der gemahlenen Körner (1 mm) wurde nach Inkubation in gepuffertem Pansensaft über verschiedene Zeitspannen erfasst und an eine Exponentialfunktion angepasst um die GB-Parameter zu bestimmen. Um den ED des XP und der Stärke zu schätzen wurden Korrelationen mit physikalischen Parametern und chemischen Inhaltsstoffen sowie mit den in vitro Werten untersucht und schrittweise multiple lineare Regressionsanalysen angewendet. Die in situ Parameter zeigten sehr große Unterschiede zwischen den einzelnen Genotypen von Mais und Weizen. Der ED zeigte große Unterschiede für verschiedene Maisgenotypen. Der ED verschiedener Weizengenotypen war sehr ähnlich. Bei Mais konnte eine gute Übereinstimmung der GB-rate mit den in situ ermittelten Werten festgestellt werden, bei Weizen war dies nicht der Fall. Die Auswertung der Korrelationsanalyse zeigte signifikante Beziehungen zwischen dem kalkulierten ED des XP und verschiedenen Aminosäuren (AS) für beide Getreidearten. Das deutet daraufhin, dass die Proteinzusammensetzung der Getreide einen Einfluss auf den XP-Abbau im Pansen hat. Bei Mais zeigten dieselben AS eine ähnliche Beziehung zum ED der Stärke, das verdeutlicht den Einfluss der Proteinzusammensetzung auf den Stärkeabbau im Pansen bei dieser Getreideart. Für beide Getreidearten konnten der ED der Stärke und des XP mit ausreichender Genauigkeit aus physikalischen und chemischen Eigenschaften, oder in Kombination mit den GB-Werten, geschätzt werden. Die Schätzgleichungen der vorliegenden Arbeit können daher dafür verwendet werden, schnell und kostengünstig Informationen zum ruminalen XP- und Stärkeabbau für Mais und Weizen zu erhalten. Die Ergebnisse der vorliegenden Arbeit zeigen eine bedeutende Variation des ruminalen XP- und Stärkeabbaus zwischen verschiedenen Maisgenotypen. In etwas geringerem Ausmaß gilt dies auch für Weizen. Bei höheren Mengen von Mais oder Weizen in der Ration, sollten die Unterschiede im ED der Stärke bei der Rationsformulierung berücksichtigt werden. Bei Mais sollte auch der ED des XP beachtet werden

Automatic design of analogue circuits

Evolvable Hardware (EHW) is a promising area in electronics today. Evolutionary Algorithms (EA), together with a circuit simulation tool or real hardware, automatically designs a circuit for a given problem. The circuits evolved may have unconventional designs and be less dependent on the personal knowledge of a designer. Nowadays, EA are represented by Genetic Algorithms (GA), Genetic Programming (GP) and Evolutionary Strategy (ES). While GA is definitely the most popular tool, GP has rapidly developed in recent years and is notable by its outstanding results. However, to date the use of ES for analogue circuit synthesis has been limited to a few applications. This work is devoted to exploring the potential of ES to create novel analogue designs. The narrative of the thesis starts with a framework of an ES-based system generating simple circuits, such as low pass filters. Then it continues with a step-by-step progression to increasingly sophisticated designs that require additional strength from the system. Finally, it describes the modernization of the system using novel techniques that enable the synthesis of complex multi-pin circuits that are newly evolved. It has been discovered that ES has strong power to synthesize analogue circuits. The circuits evolved in the first part of the thesis exceed similar results made previously using other techniques in a component economy, in the better functioning of the evolved circuits and in the computing power spent to reach the results. The target circuits for evolution in the second half are chosen by the author to challenge the capability of the developed system. By functioning, they do not belong to the conventional analogue domain but to applications that are usually adopted by digital circuits. To solve the design tasks, the system has been gradually developed to support the ability of evolving increasingly complex circuits. As a final result, a state-of-the-art ES-based system has been developed that possesses a novel mutation paradigm, with an ability to create, store and reuse substructures, to adapt the mutation, selection parameters and population size, utilize automatic incremental evolution and use the power of parallel computing. It has been discovered that with the ability to synthesis the most up-to-date multi-pin complex analogue circuits that have ever been automatically synthesized before, the system is capable of synthesizing circuits that are problematic for conventional design with application domains that lay beyond the conventional application domain for analogue circuits.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The New Hampshire, Vol. 82, No. 43 (Apr. 7, 1992)

The student publication of the University of New Hampshire

Distributed cognition and businesses as 'mental institutions'

This thesis explores distributed cognition within the context of business and argues that businesses can be considered ‘mental institutions’. It therefore defends a liberal view of cognition, recognising the integration of stakeholders within a larger business structure that contains multiple cognitive schemas that conduct, constrain, and amplify one’s thoughts and affectivity in relation to the organisation. The aim of this thesis is therefore to broaden the scope of investigation regarding the socially extended mind and demonstrate the real-world applicability of these discussions to business consultancy. Following a revision of how the ‘mental institution’ should be considered and a deconstruction of the concept of ‘business’, the thesis picks out six institutional artefacts and structures that are common features of business organisations. These are logos, products, shops, offices, hierarchies, and narratives. Mental business institutions are designed with cognition in mind, and thus these institutional features can become integral parts of thought for both employees within business organisations and external consumers. Chapters individually explore the various ways we can become coupled to these artefacts and structures as internal or external stakeholders, and thus integrated within the cognitive niche of the business institution. Finally, an empirical study of a large UK-based utility company provides an example of how one can investigate the collaborative efforts of employees within an organisation through the lens of distributed cognition. Ultimately, an application of distributed cognition and mental institutions to business within this text brings to fruition new additional conceptual resources for management and marketing studies

Involuntary childlessness: an interpretative phenomenological analysis of black women’s experiences in Luton

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the award of Master of Philosophy (MPhil).This study aimed to explore the perception and experiences of involuntary childlessness among Black African women in the UK. While there are several studies in the area of infertility, they have usually been focused on national surveys of infertility prevalence and psychological-related stress treatment from a sample selected from White and middle-class women; in addition to a growing literature on the experiences of involuntary childlessness or infertility in developing countries. However, there is a lack of research exploring the impact that ethnicity and culture could have on the perception and experience of infertility within Western societies. An interpretative phenomenological perspective informed by the philosophical principles of Martin Heidegger (1927–1962) was used to explore the experiences of eight involuntarily childless Black African women in the UK. Semi-structured interviews were used in collecting data, and analysed using Interpretative Phenomenological Analysis (IPA). Three superordinate themes emerged from the data analysis: ‘the vulnerable self’, ‘self and the social world’ and ‘coping with involuntary childlessness’ – revealing the complexities of the women’s experiences. The superordinate themes reflected a common experience shared by the women. The study revealed a concern about disclosure and exposure of their state of involuntary childlessness and the social judgement and stigma that comes with it; revealing the significant role that the community beliefs and perceptions play in the lives of the involuntarily childless women. The interviews also reveal that the experience of involuntary childlessness or infertility is one that gives rise to emotional pain, grief, loss of self-esteem, isolation and even discrimination. It is believed that the insights that this study provides will contribute to the empirical studies that have used IPA, as well as provide useful insights for infertility services in Luton as a way of ensuring that services meet the needs of the growing Black and minority ethnic population