1,284 research outputs found
A connectionist representation of first-order formulae with dynamic variable binding
The relationship between symbolicism and connectionism has been one of the major
issues in recent Artificial Intelligence research. An increasing number of researchers
from each side have tried to adopt desirable characteristics of the other. These efforts
have produced a number of different strategies for interfacing connectionist and sym¬
bolic AI. One of them is connectionist symbol processing which attempts to replicate
symbol processing functionalities using connectionist components.In this direction, this thesis develops a connectionist inference architecture which per¬
forms standard symbolic inference on a subclass of first-order predicate calculus. Our
primary interest is in understanding how formulas which are described in a limited
form of first-order predicate calculus may be implemented using a connectionist archi¬
tecture. Our chosen knowledge representation scheme is a subset of first-order Horn
clause expressions which is a set of universally quantified expressions in first-order
predicate calculus. As a focus of attention we are developing techniques for compiling
first-order Horn clause expressions into a connectionist network. This offers practical
benefits but also forces limitations on the scope of the compiled system, since we tire, in
fact, merging an interpreter into the connectionist networks. The compilation process
has to take into account not only first-order Horn clause expressions themselves but
also the strategy which we intend to use for drawing inferences from them. Thus, this
thesis explores the extent to which this type of a translation can build a connectionist
inference model to accommodate desired symbolic inference.This work first involves constructing efficient connectionist mechanisms to represent
basic symbol components, dynamic bindings, basic symbolic inference procedures, and
devising a set of algorithms which automatically translates input descriptions to neural
networks using the above connectionist mechanisms. These connectionist mechanisms
are built by taking an existing temporal synchrony mechanism and extending it further
to obtain desirable features to represent and manipulate basic symbol structures. The
existing synchrony mechanism represents dynamic bindings very efficiently using tem¬
poral synchronous activity between neuron elements but it has fundamental limitations
in supporting standard symbolic inference. The extension addresses these limitations.The ability of the connectionist inference model was tested using various types of first
order Horn clause expressions. The results showed that the proposed connectionist in¬
ference model was able to encode significant sets of first order Horn clause expressions
and replicated basic symbolic styles of inference in a connectionist manner. The system
successfully demonstrated not only forward chaining but also backward chaining over
the networks encoding the input expressions. The results, however, also showed that
implementing a connectionist mechanism for full unification among groups of unifying
arguments in rules, are encoding some types of rules, is difficult to achieve in a con¬
nectionist manner needs additional mechanisms. In addition, some difficult issues such
as encoding rules having recursive definitions remained untouched
Review of ”Bioinformatics for vaccinology“ edited by Darren R. Flower
Book review of "Bioinformatics for vaccinology" edited by Darren R. Flower
Politische Bildung in Südkorea
Wenn auch die rechtlichen Grundlagen für politische Bildung schon geschaffen wurden, mangelt es noch an weiterführenden Gesetzen und Institutionen, um entsprechende Bildungsprogramme in die Realität umzusetzen. Umfassende Exekutivorgane wie die deutsche Bundeszentrale für politische Bildung (BPB) und damit verbundene Gesetze sind notwendig. Sie werden um so wichtiger, je mehr Personal und materielle Unterstützung von autonomen Bürgerorganisationen, die im Bereich der politischen Bildung tätig sind, gebraucht werden. Eine BPB-ähnliche Organisation ist zudem notwendig, um verschiedene Veranstaltungen sowie soziale Bildungseinrichtungen effektiv durchführen bzw. verwalten zu können
Performance, Development, and Analysis of Tactile vs. Visual Receptive Fields in Texture Tasks
Texture segmentation is an effortless process in scene analysis, yet its neural
mechanisms are not sufficiently understood. A common assumption in most current
approaches is that texture segmentation is a vision problem. However, considering
that texture is basically a surface property, this assumption can at times be misleading.
One interesting possibility is that texture may be more intimately related with
touch than with vision. Recent neurophysiological findings showed that receptive
fields (RFs) for touch resemble that of vision, albeit with some subtle differences. To
leverage on this, here I propose three ways to investigate the tactile receptive fields in
the context of texture processing: (1) performance, (2) development, and (3) analysis.
For performance, I tested how such distinct properties in tactile receptive fields
can affect texture segmentation performance, as compared to that of visual receptive
fields. Preliminary results suggest that touch has an advantage over vision in texture
segmentation. These results support the idea that texture is fundamentally a tactile
(surface) property.
The next question is what drives the two types of RFs, visual and tactile, to
become different during cortical development? I investigated the possibility that
tactile RF and visual RF emerge based on the same cortical learning process, where
the only difference is in the input type, natural-scene-like vs. texture-like. The main result is that RFs trained on natural scenes develop RFs resembling visual RFs, while
those trained on texture resemble tactile RFs. These results again suggest a tight
link between texture and the tactile modality, from a developmental context.
To investigate further the functional properties of these RFs in texture processing,
the response of tactile RFs and visual RFs were analyzed with manifold learning
and with statistical approaches. The results showed that touch-based manifold seems
more suitable for texture processing and desirable properties found in visual RF response
can carry over to those in the tactile domain.
These results are expected to shed new light on the role of tactile perception
of texture; help develop more powerful, biologically inspired texture segmentation
algorithms; and further clarify the differences and similarities between touch and
vision
- …