scholarly journals Testing commutativity of a group and the power of randomization

2012 ◽  
Vol 15 ◽  
pp. 38-43 ◽  
Author(s):  
Igor Pak

AbstractLet G be a group generated by k elements, G=〈g1,…,gk〉, with group operations (multiplication, inversion and comparison with identity) performed by a black box. We prove that one can test whether the group G is abelian at a cost of O(k) group operations. On the other hand, we show that a deterministic approach requires Ω(k2) group operations.

2021 ◽  
Vol 2019 (1) ◽  
pp. 93-107
Author(s):  
Agnieszka Czejkowska ◽  
Katarina Froebus

Zusammenfassung: Der vorliegende Beitrag widmet sich Narrativen der Verunsicherung, die in Zusammenhang mit der COVID-19-Krise aufgerufen werden und für ,,innere Sicherheit“ sorgen sollen. Dabei identifizieren wir Kalküle, die einerseits individuelle Besonnenheit aktivieren und anderseits gesellschaftliche Stabilisierung gewährleisten sollen. Das gelingt uns mit Rückgriff auf psychoanalytische Subjekttheorien, die Strategien der individuellen Rationalisierung fokussieren, und auf diskursorientierte Subjekttheorien, die gesellschaftliche Disziplinierungstechnologien in den Blick nehmen.Abstract: This article is focused on narratives of uncertainness, being created during the COVID-19 crisis in order to provide ‘home security’. In doing so, we identify approaches that on the one hand activate individual level-headedness and on the other hand are supposed to ensure societal stabilization. We succeed in doing this by resorting to psychoanalytic subject theories that emphasize strategies of individual rationalization and to discourse-oriented subject theories that accent social disciplinary technologies.


2020 ◽  
Author(s):  
Zhen Liu ◽  
Qiong Huang ◽  
Duncan S Wong

Abstract Attribute-based encryption (ABE) is a versatile one-to-many encryption primitive, which enables fine-grained access control over encrypted data. Due to its promising applications in practice, ABE schemes with high efficiency, security and expressivity have been continuously emerging. On the other hand, due to the nature of ABE, a malicious user may abuse its decryption privilege. Therefore, being able to identify such a malicious user is crucial towards the practicality of ABE. Although some specific ABE schemes in the literature enjoys the tracing function, they are only proceeded case by case. Most of the ABE schemes do not support traceability. It is thus meaningful and important to have a generic way of equipping any ABE scheme with traceability. In this work, we partially solve the aforementioned problem. Namely, we propose a way of transforming (non-traceable) ABE schemes satisfying certain requirements to fully collusion-resistant black-box traceable ABE schemes, which adds only $O(\sqrt{\mathcal{K}})$ elements to the ciphertext where ${\mathcal{K}}$ is the number of users in the system. And to demonstrate the practicability of our transformation, we show how to convert a couple of existing non-traceable ABE schemes to support traceability.


2010 ◽  
Vol 09 (02) ◽  
pp. 241-256 ◽  
Author(s):  
ELEONORA GUERRINI ◽  
EMMANUELA ORSINI ◽  
MASSIMILIANO SALA

The most important families of nonlinear codes are systematic. A brute-force check is the only known method to compute their weight distribution and distance distribution. On the other hand, it outputs also all closest word pairs in the code. In the black-box complexity model, the check is optimal among closest-pair algorithms. In this paper, we provide a Gröbner basis technique to compute the weight/distance distribution of any systematic nonlinear code. Also our technique outputs all closest pairs. Unlike the check, our method can be extended to work on code families.


Author(s):  
Navid Nobani ◽  
Fabio Mercorio ◽  
Mario Mezzanzanica

Explainable Artificial Intelligence (XAI) is gaining interests in both academia and industry, mainly thanks to the proliferation of darker more complex black-box solutions which are replacing their more transparent ancestors. Believing that the overall performance of an XAI system can be augmented by considering the end-user as a human being, we are studying the ways we can improve the explanations by making them more informative and easier to use from one hand, and interactive and customisable from the other hand.


1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.


Author(s):  
A. V. Crewe

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.


Author(s):  
K.H. Westmacott

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.


2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.


Author(s):  
Stefan Krause ◽  
Markus Appel

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.


2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.


Sign in / Sign up

Export Citation Format

Share Document