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关键词： Codes   Error correction codes   Vectors   Codecs   Linear codes   Upper bound   Instruments   Hamming distances   Computer science   Nearly perfect codes   perfect codes   sphere-covering bound   weight distribution  

摘要： Nearly perfect packing codes are those codes that meet the Johnson upper bound on the size of error-correcting codes. This bound is an improvement to the sphere-packing bound. A related bound for covering codes is known as the van Wee bound. Codes that meet this bound will be called nearly perfect covering codes. This work studies such codes with covering radius 1. It is shown that the set of these codes can be partitioned into three families, depending on the distribution of the Hamming distances between neighboring codewords. General properties of these code families are presented, including a characterization of their weight and distance distributions. Constructions of codes for each of the families are presented. Finally, extended perfect covering codes are considered. Their punctured codes yield a variety of nearly perfect covering codes.

关键词： death penalty   prosecutors   sentencing   law   courts   institutions  

摘要： The U.S. criminal legal system is highly localized. This reality extends to what U.S. Supreme Court Justice Stephen Breyer called "geographic arbitrariness" in the implementation of the death penalty. The inhabited institutions perspective, augmented with concepts from Weber's sociology of law, frames our analysis of how a local process that is not arbitrary-prosecutors' interpretations of statutory aggravating factors-result in geographic arbitrariness in the aggregate, in which defendants' exposure to the death penalty is strongly conditioned by locality. We utilize data coded from prosecutors' office case files and court docket transcripts, as well as interviews with current and former District Attorneys and Assistants in Pennsylvania, to illuminate prosecutorial death penalty decisions and their interpretations of statutory aggravating factors. Our analysis is driven by two sets of questions. First, how do prosecutors differ in the filing of specific aggravating factors in the face of similar factual circumstances? Second, how do prosecutors evaluate the meaning of the aggravators and decide whether to seek the death penalty? We show that prosecutors inhabit death penalty statutory law by (1) defining statutory aggravators, drawing comparisons and contrasts from experience with prior cases;(2) making strategic assessments of how local juries will view evidence;(3) normatively evaluating individual cases, offenders, and-crucially-victims;and (4) subjectively evaluating the legal value of aggravating factors themselves. Because ambiguity in statutory aggravators necessitates differing interpretations by prosecutors, death penalty law ensures geographic arbitrariness.

关键词： Education   Technological innovation   Recruitment   Particle measurements   Data collection   Atmospheric measurements   Servers   STEM   Mathematics   Information and communication technology   Academic self-efficacy   computer science (CS)   diversity   gender   sense of belonging  

摘要： Background: The motivation behind this study stems from the gender disparity observed within undergraduate CS programs. This gender gap undermines diversity within the tech industry and hampers its potential for innovation. Research Questions: Do female CS students exhibit lower levels of school belonging and academic self-efficacy? Are there gender differences in academic achievement? What is the predictive power of prior academic performance, academic self-efficacy, and sense of belonging on first-semester grades? Methodology: In this study, 113 undergraduate students (82 males) were surveyed. The questionnaire was administered midway through the semester, in early November. High school math exam scores were assessed along with self-reported measures of academic self-efficacy and sense of belonging. Findings: The findings revealed several noteworthy observations: Female students exhibited a statistically significant higher grade point average (GPA) at the end of the first semester despite reporting lower levels of academic self-efficacy. Regression analysis identified gender, academic self-efficacy, and high school math exam scores as significant predictors of first-semester GPA. Implications: The implications of the study underscore the importance of fostering a supportive learning environment within CS education. Specifically, this study advocates for implementing teaching practices that prioritize social aspects and help enhance field-specific self-efficacy for all students.

关键词： Estimation   Imputation   Training data   IP networks   Accuracy   Supervised learning   Recommender systems   Noise   Data models   Computer science   Recommender system   collaborative filtering   debias   noise-robust learning   pairwise ranking loss  

摘要： Recommender systems have been widely employed on various online platforms to improve user experience. In these systems, recommendation models are often learned from the users' historical behaviors that are automatically collected. Notably, recommender systems differ slightly from ordinary supervised learning tasks. In recommender systems, there is an exposure mechanism that decides which items could be presented to each specific user, which breaks the i.i.d assumption of supervised learning and brings biases into the recommendation models. In this paper, we focus on unbiased ranking loss weighted by inversed propensity scores (IPS), which are widely used in recommendations with implicit feedback labels. More specifically, we first highlight the fact that there is a gap between theory and practice in IPS-weighted unbiased loss. The existing pairwise loss could be theoretically unbiased by adopting an IPS weighting scheme. Unfortunately, the propensity scores are hard to estimate due to the inaccessibility of each user-item pair's true exposure status. In practical scenarios, we can only approximate the propensity scores. In this way, the theoretically unbiased loss would be still practically biased. To solve this problem, we first construct a theoretical framework to obtain a generalization upper bound of the current theoretically unbiased loss. The bound illustrates that we can ensure the theoretically unbiased loss's generalization ability if we lower its implementation loss and practical bias at the same time. To that aim, we suggest treating feedback label Y-ui as a noisy proxy for exposure result for O-ui each user-item pair (u,i). Here we assume the noise rate meets the condition that (P) over cap O-ui=1, Y-ui not equal O-ui) < 1/2. According to our analysis, this is a mild assumption that can be satisfied by many real-world applications. Based on this, we could train an accurate propensity model directly by leveraging a noise-resistant loss function. Then we c

关键词： Computational thinking   Computer science   Game design   Block-based programming   Middle school   Attitudes  

摘要： Middle school students often enter Computer Science (CS) classes without previous CS or Computational Thinking (CT) instruction. This study evaluated how ***'s block-based programming curriculum affects middle school students' CT skills and attitudes toward CT and CS. Sixteen students participated in the study. This was a mixed methods action research study that used pre- and post-tests, surveys, artifacts, and interviews as data sources. Descriptive statistics, paired samples t-tests, and inductive thematic analysis were administered. Findings showed a statistically significant increase in participants' algorithmic thinking, debugging, and pattern recognition skills but not in abstraction skills. Attitudes toward CT and CS improved but the difference was not statistically significant. Qualitative themes revealed benefits of game-based learning to promote CT skills, collaboration to promote successful error debugging, and enjoyment of programming resulting from a balance between structured guidance and creative freedom. Findings emphasize the importance of low-threshold and engaging strategies to introduce novice learners to CT and CS.

关键词： Hamming distances   Graph theory   Error correction codes   Eigenvalues and eigenfunctions   Color   Random variables   Indexes   Geometry   Computer science   Bounds on codes   expander graphs   proper colorings   sphere packing  

摘要： We introduce graphical error-correcting codes, a new notion of error-correcting codes on [q](n) where a code is a set of proper q-colorings of some fixed n-vertex graph G. We then say that a set of M proper q-colorings of G form a (G,M,d) code if any pair of colorings in the set have Hamming distance at least d. This directly generalizes typical (n,M,d) codes of q-ary strings of length n since we can take G as the empty graph on n vertices. We investigate how one-sided spectral expansion relates to the largest possible set of error-correcting colorings on a graph. For fixed (delta,lambda)is an element of[0,1]x[-1,1] and positive integer d, let f(delta,lambda,d)(n) denote the maximum M such that there exists some d-regular graph G on at most n vertices with normalized second eigenvalue at most lambda that has a (G,M,d) code. We study the growth of f as n goes to infinity. We partially characterize the regimes of (delta,lambda) where f grows exponentially or is bounded by a constant, respectively. We also prove several sharp phase transitions between these regimes.

关键词： Cloud computing   Security   Resource management   Virtual machines   Surveys   Computer science   Virtual machine monitors   Social networking (online)   Servers   Access control   Cyber threats   hypervisor vulnerability   resource utilization (RU)   secure resource management (SRM)   virtual machine (VM) vulnerability  

摘要： Secure resource management (SRM) within a cloud computing environment is a critical yet infrequently studied research topic. This article provides a comprehensive survey and comparative performance evaluation of potential cyber threat countermeasure strategies that address security challenges during cloud workload execution and resource management. Cybersecurity is explored specifically in the context of cloud resource management, with an emphasis on identifying the associated challenges. The cyber threat countermeasure methods are categorized into three classes: defensive strategies, mitigating strategies, and hybrid strategies. The existing countermeasure strategies belonging to each class are thoroughly discussed and compared. In addition to conceptual and theoretical analysis, the leading countermeasure strategies within these categories are implemented on a common platform and examined using two real-world virtual machine (VM) data traces. Based on this comprehensive study and performance evaluation, this article discusses the tradeoffs among these countermeasure strategies and their utility, providing imperative concluding remarks on the holistic study of cloud cyber threat countermeasures and SRM. Furthermore, the study suggests future methodologies that could effectively address the emerging challenges of secure cloud resource management.

关键词： Data models   Linear matrix inequalities   Noise measurement   Symmetric matrices   Stability analysis   Closed loop systems   Vectors   Numerical stability   Convergence   Computer science   Data informativity   data-driven control   model reference control (MRC)   quadratic matrix inequalities  

摘要： The objective of model reference control is to design a controller that regulates the system's behavior so as to match a specified reference model. This article investigates necessary and sufficient conditions for model reference control from a data-driven perspective, when only a set of data generated by the system is utilized to directly accomplish the matching. Noiseless and noisy data settings are both considered. Notably, all methods we propose build on the concept of data informativity and do not rely on persistently exciting data.

关键词： digital game-based training   intellectual disability   life skill training   motivational model  

摘要： Background For learners with intellectual disability, it is a challenge and crucial issue to foster their life skills. These learners generally encounter several problems during the learning process, such as difficulties paying and maintaining attention, difficulties with memory and application and slow learning ability. Life skills training can help them facilitate their physical functions, maintain cognitive memory ability and strengthen their ability to play a greater role in society. Objective Conventional training for learners with intellectual disabilities is generally taught with traditional lectures and demonstrations, which could lack interaction and immediate feedback. To address this issue, by referring to the attention, relevance confidence and satisfaction motivational model, a digital game-based training approach is proposed. Method To confirm the effectiveness of the approach, this study experimented with a life skills training course for learners with intellectual disabilities using a pre- and post-test design for 6 months. One class of learners comprised the experimental group trained with the digital game, while the other class was the control group that learned with conventional training. The learners' learning achievement, anxiety level, learning attitude, problem-solving tendency, learning satisfaction and learning perceptions were assessed. Results and Conclusions The findings indicate that digital game-based training enhanced the learning achievement, learning attitudes, problem-solving tendency and learning satisfaction of students with intellectual disabilities, while also reducing their anxiety levels.

关键词： computer science   information systems   Word   typesetting  

摘要： Complex industrial systems consist of many heterogeneous devices running different hardware and software in a connected, layer-organized environment. Since all these software instances must be updated occasionally, and since they could affect the layers under and above, the definition of deployment strategies that will reduce downtime is necessary. In previous work, we focused on identifying common problems in software update processes and concentrated on the most effective update strategies running at the lowest (Internet of Things-IoT) and highest (Enterprise Resource Planning-ERP) levels. The result was a set of recommendations and strategies that should help minimize network utilization and processing resources and make the process as energy-efficient as possible. After that, the core effort of the research is shifted toward the Manufacturing Execution System (MES) layer-the layer that brings the higher complexity, both in terms of connectivity and software complexity. Following the actual Industry 4.0 paradigm, the software in the MES layer becomes even more critical since it is expected to integrate a whole new set of responsibilities previously belonging to various levels or external solutions. To facilitate further requests, deployment strategies are reevaluated and enriched with innovative approaches such as A/B testing and the separate update service. This paper shows the possible further development of the hybrid software deployment system when applied to the multiconnected levels, such as the MES. The adaptation shows positive results regarding the network load distribution and significant effort reduction when a rollback is needed.