Invited speaker 1
Konstantinos I. Diamantaras
"Applying PCA neural models for the blind separation of signals"
It is well known that the biologically motivated
Hebbian self-organizing principle is related to Principal Component
Analysis, a classical second-order feature extraction method. Furthermore,
various neural models have been proposed in the past implementing
a wide range of PCA extensions including Nonlinear PCA (NLPCA) and
Oriented PCA (OPCA). Nonlinear PCA, in particular, has been linked
to Independent Component Analysis, a higher order method for the
analysis of linear, instantaneous mixtures into independent constituent
components. ICA is a class of Blind Signal Separation (BSS) problems.
It is widely believed that PCA is good only for the spatial pre-whitening
of the input signals and it cannot be applied to the BSS problem.
In this talk we shall demonstrate the connection between PCA with
the solution of the BSS problem under typical second-order assumptions.
We shall show that PCA or Oriented PCA, in conjunction with temporal
filtering, lead to the solution of BSS. The selection of the optimal
filter is still an open issue. The advantage of using PCA neural
models is that they can be directly applied to large scale problems
without explicitly computing the data covariance matrix. The method
is tested using simulated data and compared against standard second
Invited speaker 2
"Modal Learning in Neural Networks"
The trend in neural computing is to have a single
weight update equation or learning method. There are now several
forms of learning commonly utilised in various types of neural networks.
These include error minimisation techniques including the famous
backpropagation; Bayesian methods; and Learning Vector Quantization;
as well as related methods such as Support Vector Machines. Hybrid
systems do combine types of learning by utilising more than one
network, often in a modular framework. However, it is uncommon for
learning methods to be integrated into a single network; even though
there is no biological or cognitive evidence on which to base the
assumption that neurons are restricted to a single learning mode.
There are several reasons to explore modal learning in neural networks.
Modal refers to networks in which neurons adopt one of two or more
learning modes (such as different weight update equations) and may
swap between them during learning. One motivation is to overcome
the inherent limitations of any given mode; another is inspiration
from neuroscience, cognitive science and human learning; a third
reason is the challenge of dealing with non-stationary input data,
or time-variant learning objectives. Three modal learning ideas
will be presented, with examples: The Snap-Drift Neural Network
(SDNN) which toggles its learning between two modes, either unsupervised
or guided by performance feedback (reinforcement); a general approach
to swapping between several learning modes in real-time; and an
adaptive function neural network, in which adaptation applies simultaneously
to both the weights and the individual neuron activation functions.
Examples will be drawn from a range of applications such as natural
language parsing, speech processing, geographical location systems,
the Iris dataset, user modelling, optical character recognition
and virtual learning environments.
Invited speaker 3
"Towards knowledge-based neural networks: At the junction
of fuzzy sets and neurocomputing"
In this talk, we focus on the fundamentals and
development issues of logic-driven constructs of fuzzy neural networks.
These networks constitute an interesting conceptual and computational
framework that benefits from the establishment of highly synergistic
links between the technology of fuzzy sets and neural networks.
The evident advantages of knowledge-based networks
are twofold. First, the transparency of neural architectures becomes
highly relevant when dealing with the mechanisms of efficient learning
which is enabled by the fact that domain knowledge could be easily
incorporated in advance prior to any learning. This becomes possible
given the compatibility between the architecture of the problem
and the induced topology of the neural network. Second, once the
training has been completed, the network is highly interpretable
and thus directly translates into a series of truth-quantifiable
logic expressions formed over a collection of information granules.
The design process of the logic networks synergistically
exploits the principles of information granulation, logic computing
and underlying optimization including those biologically inspired
techniques (such as particle swarm optimization, genetic algorithms
and alike). We elaborate on the existing development trends, present
key methodological pursuits and algorithms as well as discuss some
example applications. In particular, we show how the logic blueprint
of the networks is supported by the use of various constructs of
fuzzy sets including logic operators, logic neurons, referential
operators and fuzzy relational constructs.