3 research outputs found
Explanations of Black-Box Model Predictions by Contextual Importance and Utility
The significant advances in autonomous systems together with an immensely
wider application domain have increased the need for trustable intelligent
systems. Explainable artificial intelligence is gaining considerable attention
among researchers and developers to address this requirement. Although there is
an increasing number of works on interpretable and transparent machine learning
algorithms, they are mostly intended for the technical users. Explanations for
the end-user have been neglected in many usable and practical applications. In
this work, we present the Contextual Importance (CI) and Contextual Utility
(CU) concepts to extract explanations that are easily understandable by experts
as well as novice users. This method explains the prediction results without
transforming the model into an interpretable one. We present an example of
providing explanations for linear and non-linear models to demonstrate the
generalizability of the method. CI and CU are numerical values that can be
represented to the user in visuals and natural language form to justify actions
and explain reasoning for individual instances, situations, and contexts. We
show the utility of explanations in car selection example and Iris flower
classification by presenting complete (i.e. the causes of an individual
prediction) and contrastive explanation (i.e. contrasting instance against the
instance of interest). The experimental results show the feasibility and
validity of the provided explanation methods
Nature-inspired optimisation: Improvements to the Particle Swarm Optimisation Algorithm and the Bees Algorithm
This research focuses on nature-inspired optimisation algorithms, in particular, the Particle Swarm Optimisation (PSO) Algorithm and the Bees Algorithm. The PSO Algorithm is a population-based stochastic optimisation technique first invented in 1995. It was inspired by the social behaviour of birds flocking or a school of fish. The Bees Algorithm is a population-based search algorithm initially proposed in 2005. It mimics the food foraging behaviour of swarms of honey bees. The thesis presents three algorithms. The first algorithm called the PSO-Bees Algorithm is a cross between the PSO Algorithm and the Bees Algorithm. The PSO-Bees Algorithm enhanced the PSO Algorithm with techniques derived from the Bees Algorithm. The second algorithm called the improved Bees Algorithm is a version of the Bees Algorithm that incorporates techniques derived from the PSO Algorithm. The third algorithm called the SNTO-Bees Algorithm enhanced the Bees Algorithm using techniques derived from the Sequential Number-Theoretic Optimisation (SNTO) Algorithm. To demonstrate the capability of the proposed algorithms, they were applied to different optimisation problems. The PSO-Bees Algorithm is used to train neural networks for two problems, Control Chart Pattern Recognition and Wood Defect Classification. The results obtained and those from tests on well known benchmark functions provide an indication of the performance of the algorithm relative to that of other swarm-based stochastic optimisation algorithms. The improved Bees Algorithm was applied to mechanical design optimisation problems (design of welded beams and coil springs) and the mathematical benchmark problems used previously to test the PSO-Bees Algorithm. The algorithm incorporates cooperation and communication between different neighbourhoods. The results obtained show that the proposed cooperation and communication strategies adopted enhanced the performance and convergence of the algorithm. The SNTO-Bees Algorithm was applied to a set of mechanical design optimisation problems (design of welded beams, coil springs and pressure vessel) and mathematical benchmark functions used previously to test the PSO-Bees Algorithm and the improved Bees Algorithm. In addition, the algorithm was tested with a number of deceptive multi modal benchmark functions. The results obtained help to validate the SNTO-Bees Algorithm as an effective global optimiser capable of handling problems that are deceptive in nature with high dimensions