1,326 research outputs found
Competent Program Evolution, Doctoral Dissertation, December 2006
Heuristic optimization methods are adaptive when they sample problem solutions based on knowledge of the search space gathered from past sampling. Recently, competent evolutionary optimization methods have been developed that adapt via probabilistic modeling of the search space. However, their effectiveness requires the existence of a compact problem decomposition in terms of prespecified solution parameters. How can we use these techniques to effectively and reliably solve program learning problems, given that program spaces will rarely have compact decompositions? One method is to manually build a problem-specific representation that is more tractable than the general space. But can this process be automated? My thesis is that the properties of programs and program spaces can be leveraged as inductive bias to reduce the burden of manual representation-building, leading to competent program evolution. The central contributions of this dissertation are a synthesis of the requirements for competent program evolution, and the design of a procedure, meta-optimizing semantic evolutionary search (MOSES), that meets these requirements. In support of my thesis, experimental results are provided to analyze and verify the effectiveness of MOSES, demonstrating scalability and real-world applicability
A Field Guide to Genetic Programming
xiv, 233 p. : il. ; 23 cm.Libro ElectrónicoA Field Guide to Genetic Programming (ISBN 978-1-4092-0073-4) is an introduction to genetic programming (GP). GP is a systematic, domain-independent method for getting computers to solve problems automatically starting from a high-level statement of what needs to be done. Using ideas from natural evolution, GP starts from an ooze of random computer programs, and progressively refines them through processes of mutation and sexual recombination, until solutions emerge. All this without the user having to know or specify the form or structure of solutions in advance. GP has generated a plethora of human-competitive results and applications, including novel scientific discoveries and patentable inventions. The authorsIntroduction --
Representation, initialisation and operators in Tree-based GP --
Getting ready to run genetic programming --
Example genetic programming run --
Alternative initialisations and operators in Tree-based GP --
Modular, grammatical and developmental Tree-based GP --
Linear and graph genetic programming --
Probalistic genetic programming --
Multi-objective genetic programming --
Fast and distributed genetic programming --
GP theory and its applications --
Applications --
Troubleshooting GP --
Conclusions.Contents
xi
1 Introduction
1.1 Genetic Programming in a Nutshell
1.2 Getting Started
1.3 Prerequisites
1.4 Overview of this Field Guide I
Basics
2 Representation, Initialisation and GP
2.1 Representation
2.2 Initialising the Population
2.3 Selection
2.4 Recombination and Mutation Operators in Tree-based
3 Getting Ready to Run Genetic Programming 19
3.1 Step 1: Terminal Set 19
3.2 Step 2: Function Set 20
3.2.1 Closure 21
3.2.2 Sufficiency 23
3.2.3 Evolving Structures other than Programs 23
3.3 Step 3: Fitness Function 24
3.4 Step 4: GP Parameters 26
3.5 Step 5: Termination and solution designation 27
4 Example Genetic Programming Run
4.1 Preparatory Steps 29
4.2 Step-by-Step Sample Run 31
4.2.1 Initialisation 31
4.2.2 Fitness Evaluation Selection, Crossover and Mutation Termination and Solution Designation Advanced Genetic Programming
5 Alternative Initialisations and Operators in
5.1 Constructing the Initial Population
5.1.1 Uniform Initialisation
5.1.2 Initialisation may Affect Bloat
5.1.3 Seeding
5.2 GP Mutation
5.2.1 Is Mutation Necessary?
5.2.2 Mutation Cookbook
5.3 GP Crossover
5.4 Other Techniques 32
5.5 Tree-based GP 39
6 Modular, Grammatical and Developmental Tree-based GP 47
6.1 Evolving Modular and Hierarchical Structures 47
6.1.1 Automatically Defined Functions 48
6.1.2 Program Architecture and Architecture-Altering 50
6.2 Constraining Structures 51
6.2.1 Enforcing Particular Structures 52
6.2.2 Strongly Typed GP 52
6.2.3 Grammar-based Constraints 53
6.2.4 Constraints and Bias 55
6.3 Developmental Genetic Programming 57
6.4 Strongly Typed Autoconstructive GP with PushGP 59
7 Linear and Graph Genetic Programming 61
7.1 Linear Genetic Programming 61
7.1.1 Motivations 61
7.1.2 Linear GP Representations 62
7.1.3 Linear GP Operators 64
7.2 Graph-Based Genetic Programming 65
7.2.1 Parallel Distributed GP (PDGP) 65
7.2.2 PADO 67
7.2.3 Cartesian GP 67
7.2.4 Evolving Parallel Programs using Indirect Encodings 68
8 Probabilistic Genetic Programming
8.1 Estimation of Distribution Algorithms 69
8.2 Pure EDA GP 71
8.3 Mixing Grammars and Probabilities 74
9 Multi-objective Genetic Programming 75
9.1 Combining Multiple Objectives into a Scalar Fitness Function 75
9.2 Keeping the Objectives Separate 76
9.2.1 Multi-objective Bloat and Complexity Control 77
9.2.2 Other Objectives 78
9.2.3 Non-Pareto Criteria 80
9.3 Multiple Objectives via Dynamic and Staged Fitness Functions 80
9.4 Multi-objective Optimisation via Operator Bias 81
10 Fast and Distributed Genetic Programming 83
10.1 Reducing Fitness Evaluations/Increasing their Effectiveness 83
10.2 Reducing Cost of Fitness with Caches 86
10.3 Parallel and Distributed GP are Not Equivalent 88
10.4 Running GP on Parallel Hardware 89
10.4.1 Master–slave GP 89
10.4.2 GP Running on GPUs 90
10.4.3 GP on FPGAs 92
10.4.4 Sub-machine-code GP 93
10.5 Geographically Distributed GP 93
11 GP Theory and its Applications 97
11.1 Mathematical Models 98
11.2 Search Spaces 99
11.3 Bloat 101
11.3.1 Bloat in Theory 101
11.3.2 Bloat Control in Practice 104
III
Practical Genetic Programming
12 Applications
12.1 Where GP has Done Well
12.2 Curve Fitting, Data Modelling and Symbolic Regression
12.3 Human Competitive Results – the Humies
12.4 Image and Signal Processing
12.5 Financial Trading, Time Series, and Economic Modelling
12.6 Industrial Process Control
12.7 Medicine, Biology and Bioinformatics
12.8 GP to Create Searchers and Solvers – Hyper-heuristics xiii
12.9 Entertainment and Computer Games 127
12.10The Arts 127
12.11Compression 128
13 Troubleshooting GP
13.1 Is there a Bug in the Code?
13.2 Can you Trust your Results?
13.3 There are No Silver Bullets
13.4 Small Changes can have Big Effects
13.5 Big Changes can have No Effect
13.6 Study your Populations
13.7 Encourage Diversity
13.8 Embrace Approximation
13.9 Control Bloat
13.10 Checkpoint Results
13.11 Report Well
13.12 Convince your Customers
14 Conclusions
Tricks of the Trade
A Resources
A.1 Key Books
A.2 Key Journals
A.3 Key International Meetings
A.4 GP Implementations
A.5 On-Line Resources 145
B TinyGP 151
B.1 Overview of TinyGP 151
B.2 Input Data Files for TinyGP 153
B.3 Source Code 154
B.4 Compiling and Running TinyGP 162
Bibliography 167
Inde
Interpreting CLIP with Sparse Linear Concept Embeddings (SpLiCE)
CLIP embeddings have demonstrated remarkable performance across a wide range
of computer vision tasks. However, these high-dimensional, dense vector
representations are not easily interpretable, restricting their usefulness in
downstream applications that require transparency. In this work, we empirically
show that CLIP's latent space is highly structured, and consequently that CLIP
representations can be decomposed into their underlying semantic components. We
leverage this understanding to propose a novel method, Sparse Linear Concept
Embeddings (SpLiCE), for transforming CLIP representations into sparse linear
combinations of human-interpretable concepts. Distinct from previous work,
SpLiCE does not require concept labels and can be applied post hoc. Through
extensive experimentation with multiple real-world datasets, we validate that
the representations output by SpLiCE can explain and even replace traditional
dense CLIP representations, maintaining equivalent downstream performance while
significantly improving their interpretability. We also demonstrate several use
cases of SpLiCE representations including detecting spurious correlations,
model editing, and quantifying semantic shifts in datasets.Comment: 17 pages, 8 figures, Code is provided at
https://github.com/AI4LIFE-GROUP/SpLiC
Recommended from our members
Bayesian methods for knowledge transfer and policy search in reinforcement learning
How can an agent generalize its knowledge to new circumstances? To learn
effectively an agent acting in a sequential decision problem must make intelligent action selection choices based on its available knowledge. This dissertation focuses on Bayesian methods of representing learned knowledge and develops novel algorithms that exploit the represented
knowledge when selecting actions.
Our first contribution introduces the multi-task Reinforcement
Learning setting in which an agent solves a sequence of tasks. An
agent equipped with knowledge of the relationship between tasks can
transfer knowledge between them. We propose the transfer of two
distinct types of knowledge: knowledge of domain models and knowledge
of policies. To represent the transferable knowledge, we propose
hierarchical Bayesian priors on domain models and policies
respectively. To transfer domain model knowledge, we introduce a new
algorithm for model-based Bayesian Reinforcement Learning in the
multi-task setting which exploits the learned hierarchical Bayesian
model to improve exploration in related tasks. To transfer policy
knowledge, we introduce a new policy search algorithm that accepts a
policy prior as input and uses the prior to bias policy search. A
specific implementation of this algorithm is developed that accepts a
hierarchical policy prior. The algorithm learns the hierarchical
structure and reuses components of the structure in related tasks.
Our second contribution addresses the basic problem of generalizing knowledge gained from previously-executed policies. Bayesian
Optimization is a method of exploiting a prior model of an objective function to quickly identify the point maximizing the modeled objective.
Successful use of Bayesian Optimization in Reinforcement Learning
requires a model relating policies and their performance. Given such a
model, Bayesian Optimization can be applied to search for an optimal
policy. Early work using Bayesian Optimization in the Reinforcement
Learning setting ignored the sequential nature of the underlying
decision problem. The work presented in this thesis explicitly
addresses this problem. We construct new Bayesian models that take
advantage of sequence information to better generalize knowledge
across policies. We empirically evaluate the value of this approach in
a variety of Reinforcement Learning benchmark problems. Experiments
show that our method significantly reduces the amount of exploration
required to identify the optimal policy.
Our final contribution is a new framework for learning parametric
policies from queries presented to an expert. In many domains it is
difficult to provide expert demonstrations of desired policies.
However, it may still be a simple matter for an expert to identify
good and bad performance. To take advantage of this limited expert
knowledge, our agent presents experts with pairs of demonstrations and
asks which of the demonstrations best represents a latent target
behavior. The goal is to use a small number of queries to elicit the
latent behavior from the expert. We formulate a Bayesian model of the
querying process, an inference procedure that estimates the posterior
distribution over the latent policy space, and an active procedure for
selecting new queries for presentation to the expert. We show, in
multiple domains, that the algorithm successfully learns the target
policy and that the active learning strategy generally improves the
speed of learning
my Human Brain Project (mHBP)
How can we make an agent that thinks like us humans? An agent that can have
proprioception, intrinsic motivation, identify deception, use small amounts of energy, transfer
knowledge between tasks and evolve? This is the problem that this thesis is focusing on.
Being able to create a piece of software that can perform tasks like a human being, is
a goal that, if achieved, will allow us to extend our own capabilities to a very high level, and
have more tasks performed in a predictable fashion. This is one of the motivations for this
thesis.
To address this problem, we have proposed a modular architecture for
Reinforcement Learning computation and developed an implementation to have this
architecture exercised. This software, that we call mHBP, is created in Python using Webots
as an environment for the agent, and Neo4J, a graph database, as memory. mHBP takes
the sensory data or other inputs, and produces, based on the body parts / tools that the
agent has available, an output consisting of actions to perform.
This thesis involves experimental design with several iterations, exploring a
theoretical approach to RL based on graph databases. We conclude, with our work in this
thesis, that it is possible to represent episodic data in a graph, and is also possible to
interconnect Webots, Python and Neo4J to support a stable architecture for Reinforcement
Learning. In this work we also find a way to search for policies using the Neo4J querying
language: Cypher. Another key conclusion of this work is that state representation needs to
have further research to find a state definition that enables policy search to produce more
useful policies.
The article “REINFORCEMENT LEARNING: A LITERATURE REVIEW (2020)” at
Research Gate with doi 10.13140/RG.2.2.30323.76327 is an outcome of this thesis.Como podemos criar um agente que pense como nós humanos? Um agente que tenha
propriocepção, motivação intrínseca, seja capaz de identificar ilusão, usar pequenas
quantidades de energia, transferir conhecimento entre tarefas e evoluir? Este é o problema
em que se foca esta tese.
Ser capaz de criar uma peça de software que desempenhe tarefas como um ser
humano é um objectivo que, se conseguido, nos permitirá estender as nossas capacidades
a um nível muito alto, e conseguir realizar mais tarefas de uma forma previsível. Esta é uma
das motivações desta tese.
Para endereçar este problema, propomos uma arquitectura modular para
computação de aprendizagem por reforço e desenvolvemos uma implementação para
exercitar esta arquitetura. Este software, ao qual chamamos mHBP, foi criado em Python
usando o Webots como um ambiente para o agente, e o Neo4J, uma base de dados de
grafos, como memória. O mHBP recebe dados sensoriais ou outros inputs, e produz,
baseado nas partes do corpo / ferramentas que o agente tem disponíveis, um output que
consiste em ações a desempenhar.
Uma boa parte desta tese envolve desenho experimental com diversas iterações,
explorando uma abordagem teórica assente em bases de dados de grafos. Concluímos,
com o trabalho nesta tese, que é possível representar episódios em um grafo, e que é,
também, possível interligar o Webots, com o Python e o Neo4J para suportar uma
arquitetura estável para a aprendizagem por reforço. Neste trabalho, também, encontramos
uma forma de procurar políticas usando a linguagem de pesquisa do Neo4J: Cypher. Outra
conclusão chave deste trabalho é que a representação de estados necessita de mais
investigação para encontrar uma definição de estado que permita à pesquisa de políticas
produzir políticas que sejam mais úteis.
O artigo “REINFORCEMENT LEARNING: A LITERATURE REVIEW (2020)” no
Research Gate com o doi 10.13140/RG.2.2.30323.76327 é um sub-produto desta tese
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