Pub. online:5 Aug 2022Type:Research ArticleOpen Access
Journal:Informatica
Volume 16, Issue 2 (2005), pp. 159–174
Abstract
The more realistic neural soma and synaptic nonlinear relations and an alternative mean field theory (MFT) approach relevant for strongly interconnected systems as a cortical matter are considered. The general procedure of averaging the quenched random states in the fully-connected networks for MFT, as usually, is based on the Boltzmann Machine learning. But this approach requires an unrealistically large number of samples to provide a reliable performance. We suppose an alternative MFT with deterministic features instead of stochastic nature of searching a solution a set of large number equations. Of course, this alternative theory will not be strictly valid for infinite number of elements. Another property of generalization is an inclusion of the additional member in the effective Hamiltonian allowing to improve the stochastic hill-climbing search of the solution not dropping into local minima of the energy function. Especially, we pay attention to increasing of neural networks retrieval capability transforming the replica-symmetry model by including of different nonlinear elements. Some results of numerical modeling as well as the wide discussion of neural systems storage capacity are presented.
Pub. online:17 Jun 2022Type:Research ArticleOpen Access
Journal:Informatica
Volume 33, Issue 2 (2022), pp. 225–246
Abstract
The paper presents a secure and usable variant of the Game Changer Password System, first proposed by McLennan, Manning, and Tuft. Unlike the initial proposal based on inadequately secure Monopoly and Chess, we propose an improved version based on a layered “Battleship” game resilient against brute force and dictionary attacks. Since the initially proposed scheme did not check for the memorability and usability of a layered version, we conducted an experiment on the usability and memorability aspects. Surprisingly, layered passwords are just as memorable as single ones and, with an 80% recall rate, comparable to other graphical password systems. The claim that memorability is the most vital aspect of game-based password systems cannot be disproved. However, the experiment revealed that the usability decreased to such a low level that users felt less inclined to use such a system daily or recommend it to others.
Our study has once again shown that optimizing the password security–memorability–usability triangle is hard to achieve without compromising one of its cornerstones. However, the layered Game Changer Password System can be used in specific applications where usability is of secondary importance, while security and memorability augmented by its graphical interface are at the forefront.
Journal:Informatica
Volume 9, Issue 2 (1998), pp. 141–160
Abstract
The nonlinearities play a crucial role in the brain processes. They take place in neuronal system elements: synapses, dendrite membranes, soma of neurons, axons. It is established that the soma nonlinearity, which is of sigmoidal shape, is not so strong as compared with the electric current-voltage relation of a dendrite membrane. The relation is N-shaped with two stable and one unstable points. In dynamics, this leads to the appearance of a switch wave or formation of some logic functions. We present some artificial logic circuits based on an electrical analogy of dendritic membrane characteristics in static and dynamic cases. The nonlinear cable theory and the numerical simulation were used. Basing on the logic circuit construction proposed, we suppose that the dendritic membrane processes are able not only to gather and transfer information but also to transform and classify knowledge.
The theoretical substantiation and numerical experiments are only the first step forward to the proving of neuronal dendritic logic constructions. Of course, extensive neurophysiological tests are necessary to discover the final mechanism of neuronal computing in the human brain.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 3–30
Abstract
Despite the vast and rich panorama of hypertext research, to date there are still no clear definitions of what hypertext really is. Classical references describe the concept “hypertext” as a non-linear way of thinking, reading, and accessing the information which is best done on the computer screen. This paper shows the present situation where hypertext is seen as the interaction between the learner and an information source; it raises questions about how information should be organised so as to promote better learning. Due to the fact that the present empirical results still show no consensus among hypertext researchers about the different representations of educational hypertexts; this paper will bring together three perspectives, in particular traditional, pedagogical and psychological points of view, in order to obtain a coherent view of the current situation in hypertext research. The traditional perspective will outline two main problems that seem endemic to hypertext: problems of navigation and cognitive overload. The pedagogical perspective will summarise the main ideas of three possible theoretical justifications of existing educational hypertexts: the ideas of concept mapping, cognitive flexibility theory, and semantic networking. The psychological perspective will evaluate hypertext from the perspective of human factors (or ergonomics).
Finally, a critical investigation of existing educational hypertexts with consideration of relevant learning theories and human activities will lead to a clearer definition of possible arenas where hypertext might be or might not be an appropriate learning tool.