bluuebunny/crossref_metadata_2025 huggingface dataset:
Health information use by patients with systemic lupus erythematosus (SLE) pre and during the COVID-19 pandemic
Authors: Cardwell Francesca S , Elliott Susan J , Chin Ricky , St Pierre Yvan , Choi May Y , Urowitz Murray B , Ruiz-Irastorza Guillermo , Bernatsky Sasha , Wallace Daniel J , Petri Michelle A , Manzi Susan , Bae Sang-Cheol , Shin Jung-Min , Mak Anselm , Cho Jiacai , Peschken Christine A , Ramsey-Goldman Rosalind , Fortin Paul R , Hanly John G , Pons-Estel Bernardo A , Nieto Romina , Askanase Anca D , Romero-Diaz Juanita , Mosca Marta , Bruce Ian N , Rowbottom Leigha , Mielczarek Leanne , Tse Karin , Marion Ashley , Cáhiz-González Juan Carlos , Cattoni Teresa G , Cornet Alain , Clarke Ann Elaine
Published: October 2022

Objective

We conducted an international survey of patients with SLE to assess their access, preference and trust in various health information sources pre-COVID-19 and during the COVID-19 pandemic.

Methods

Patients with SLE were recruited from 18 observational cohorts, and patients self-reporting SLE were recruited through five advocacy organisations. Respondents completed an online survey from June 2020 to December 2021 regarding the sources of health information they accessed in the 12 months preceding (pre-11 March 2020) and during (post-11 March 2020) the pandemic. Multivariable logistic regressions assessed factors associated with accessing news and social media post-11 March 2020, and self-reporting negative impacts from health information accessed through these sources.

Results

Surveys were completed by 2111 respondents; 92.8% were female, 76.6% had postsecondary education, mean (SD) age was 48.8 (14.0) years. Lupus specialists and family physicians were the most preferred sources pre-11 March 2020 and post-11 March 2020, yet were accessed less frequently (specialists: 78.5% pre vs 70.2% post, difference −8.3%, 95% CI −10.2% to −6.5%; family physicians: 57.1% pre vs 50.0% post, difference −7.1%, 95% CI −9.2% to −5.0%), while news (53.2% pre vs 62.1% post, difference 8.9%, 95% CI 6.7% to 11.0%) and social media (38.2% pre vs 40.6% post, difference 2.4%, 95% CI 0.7% to 4.2%) were accessed more frequently post-11 March 2020 vs pre-11 March 2020. 17.2% of respondents reported negative impacts from information accessed through news/social media. Those outside Canada, older respondents or with postsecondary education were more likely to access news media. Those in Asia, Latin America or younger respondents were more likely to access social media. Those in Asia, older respondents, males or with postsecondary education in Canada, Asia or the USA were less likely to be negatively impacted.

Conclusions

Physicians, the most preferred and trusted sources, were accessed less frequently, while news and social media, less trusted sources, were accessed more frequently post-11 March 2020 vs pre-11 March 2020. Increasing accessibility to physicians, in person and virtually, may help reduce the consequences of accessing misinformation/disinformation.
Trends in the treatment of undescended testes: a pediatric tertiary care center experience from Croatia
Authors: Bašković Marko , Zaninović Luca , Sansović Ivona , Meašić Ana Maria , Katušić Bojanac Ana , Ježek Davor
Published: October 2022

Objective

Undescended testes (UDT) is the most common anomaly of the male genitourinary tract. The guidelines suggest that orchidopexy in congenitally UDT should be performed between 6 months and 18 months of age, while in acquired UDT, orchidopexy should be performed before puberty. Delay in treatment increases the risk of cancer and infertility. The main aim of this study was to determine whether we meet international standards in the treatment of UDT.

Methods

The present study included all boys who underwent orchidopexy either due to congenital or acquired UDT in 2019 (from January 1 to December 31). For each group, laterality, location, associated anomalies, premature birth and in how many cases ultrasound was applied were determined. Additionally, for each group, the types of surgery, the number of necessary reoperations, and in how many cases atrophy occurred were determined. Finally, ages of referral, of clinical examination, and of orchidopexy were determined.

Results

During this period, 198 patients with 263 UDT underwent orchidopexy. The median time of orchidopexy for the congenital group was 30 months, while that for the acquired group was 99 months. In the congenital group up to 18 months of age, orchidopexy was performed in 16 (16%) boys, while in the acquired group up to 13 years of age, orchidopexy was performed in 95 (96.94%) boys.

Conclusion

Given the well-known risks of late treatment of UDT, orchidopexy needs to be performed much earlier, especially in the congenital group.
Differences in energy acquisition and storage of farm, wild, and hybrid Atlantic salmon competing in the wild
Authors: Crowley Samantha E. , Bradbury Ian R. , Messmer Amber M. , Duffy Steven J. , Parrish Christopher C. , Islam Shahinur S. , Fleming Ian A.
Published: October 2022

An understanding of genetic differences in fitness-related traits for farm, wild, and hybrid Atlantic salmon ( Salmo salar) is key for predicting impacts of aquaculture escapes on wild populations. Here we used lipid and fatty acid (FA) analyses to investigate differences in storage and foraging ability among Atlantic salmon juveniles of three cross types (farm, wild, and F1 hybrids), at the beginning and end of a common garden experimental release in the Newfoundland wild. We found differences in lipid class and FA profiles among cross types at both release and recapture, with farm fish being the most differentiated at recapture. In addition, low recapture levels of triacylglycerols and certain FAs indicative of freshwater prey suggest the possibility of a feeding disadvantage for farm fish. Overall, we show that lipid and FA profiles in juvenile salmon can change over just a short period of time even under favourable conditions in the wild, and farm fish may have genetic differences affecting energy acquisition and storage that could negatively impact their survival and fitness in the longer term.
EKO: evolution kernel operators
Authors: Candido Alessandro , Hekhorn Felix , Magni Giacomo
Published: October 2022

We present a new QCD evolution library for unpolarized parton distribution functions: . The program solves DGLAP equations up to next-to-next-to-leading order. The unique feature of is the computation of solution operators, which are independent of the boundary condition, can be stored and quickly applied to evolve several initial PDFs. The approach combines the power of N-space solutions with the flexibility of a x-space delivery, that allows for an easy interface with existing codes. The code is fully open source and written in Python, with a modular structure in order to facilitate usage, readability and possible extensions. We provide a set of benchmarks with similar available tools, finding good agreement.
Neutrino flavor oscillations in a rotating spacetime
Authors: Swami Himanshu
Published: October 2022

We study neutrino oscillations in a rotating spacetime under the weak gravity limit for the trajectories of neutrinos which are constrained in the equatorial plane. Using the asymptotic form of the Kerr metric, we show that the rotation of the gravitational source non-trivially modifies the neutrino phase. We find that the oscillation probabilities deviate significantly from the corresponding results in the Schwarzschild spacetime when neutrinos are produced near the black hole (still in the weak-gravity limit) with non-zero angular momentum and detected on the same side, i.e., the non-lensed neutrino. Moreover, for a given gravitational body and geometric parameters, there exists a distance scale for every energy scale (and vice versa), after which the rotational contribution in the neutrino phase becomes significant. Using the sun-sized gravitational body in the numerical analysis of the one-sided neutrino propagation, we show that even a small rotation of the gravitational object can significantly change the survival or appearance events of a neutrino flavor registered by the detector, which is located on the earth. These effects are expected to be prominent for cosmological/astrophysical scenarios where neutrinos travel past by many (rotating) gravitational bodies and for large distances. Thus rotational effects of all such bodies must be incorporated in analyzing oscillations data.
Revisiting diagonal tetrads: new Black Hole solutions in f(T) gravity
Authors: Awad Adel , Golovnev Alexey , Guzmán María-José , El Hanafy Waleed
Published: October 2022

We study various forms of diagonal tetrads that accommodate Black Hole solutions in f(T) gravity with certain symmetries. As is well-known, vacuum spherically symmetric diagonal tetrads lead to rather boring cases of constant torsion scalars. We extend this statement to other possible horizon topologies, namely, spherical, hyperbolic and planar horizons. All such cases are forced to have constant torsion scalars to satisfy the anti-symmetric part of the field equations. We give a full classification of possible vacuum static solutions of this sort. Furthermore, we discuss addition of time-dependence in all the above cases. We also show that if all the components of a diagonal tetrad depend only on one coordinate, then the anti-symmetric part of the field equations is automatically satisfied. This result applies to the flat horizon case with Cartesian coordinates. For solutions with a planar symmetry (or a flat horizon), one can naturally use Cartesian coordinates on the horizon. In this case, we show that the presence of matter is required for existence of non-trivial solutions. This is a novel and very interesting feature of these constructions. We present two new exact solutions, the first is a magnetic Black Hole which is the magnetic dual of a known electrically charged Black Hole in literature. The second is a dyonic Black Hole with electric and magnetic charges. We present some features of these Black holes, namely, extremality conditions, mass, behavior of torsion and curvature scalars near the singularity.
TEAM-BASED INNOVATION CONTESTS FOR CROWDSOURCING: AN EXPLORATORY STUDY ON IDEACONNECTION PLATFORM
Authors: HOSSAIN MOKTER , PIAZZA MARIANGELA , MAZZOLA ERICA
Published: October 2022

Crowdsourcing for innovation contests represents a promising mechanism to access and integrate external ideas. Among various crowdsourcing types, online, team-based contest is one of the most prominent one. The objective of this study is to deepen the understanding of team-based crowdsourcing by exploring specifically the issues that characterise the innovation process of crowdsourcing in a virtual team setting. To empirically pursue this aim, we conducted an interview-based case study leveraging interviews of 106 solvers and 24 facilitators moderating the team of solvers, which have participated in contests through the IdeaConnection crowdsourcing platform. We found that five main issues characterise team-based crowdsourcing competitions: Platform support, Solvers skills, Solver motivation, Solutions, and Performance. Specifically, some of these issues are in line with previous literature investigating individual crowdsourcing competition, while others are novel highlighting the peculiarity of the virtual team setting.
Some characterizations on indefinite space forms admitting almost contact structures
Authors: Acet Bilal Eftal , Gülbahar Mehmet , Kılıç Erol
Published: October 2022

In this paper, the projective curvature tensor field of a generalized indefinite Sasakian space form is investigated. Some results dealing with projectively semi-symmetric and [Formula: see text]-projectively semi-symmetric generalized indefinite Sasakian space forms are obtained. Furthermore, biharmonic Legendre Frenet curves are discussed on these manifolds.
"A Time and Phase for Everything" - Towards A Self Regulated Learning Perspective on Computational Support for Esports
Authors: Kleinman Erica , Habibi Reza , Yao Yichen , Gayle Christian , Seif El-Nasr Magy
Published: October 2022

Computational support for learning in the domain of esports has seen a great deal of attention in recent years as an effective means of helping players learn and reap the benefits of play. However, previous work has not examined the tools from a learning theory perspective to assess if learning is prompted and supported in the right place and time. As a first step towards addressing this gap, this paper presents the results of two studies: a review of existing computational tools, and an online survey of esports' players' learning needs supplemented with qualitative interviews. Using Zimmerman's Cyclical Phase Model of Self-Regulated Learning as a lens, we identify patterns in the types of support offered by existing tools and players' support interests during different learning phases. We identify 11 opportunities for future research and development to better support self-regulated learning in esports.
Beyond Just Rules: Server Rules for Shaping Positive Experiences in an Online Play Community for Youth
Authors: Jagannath Krithika , Salen Katie
Published: October 2022

Rules, a quintessential property of any and every game, are one of the factors that influence player experiences. Online multiplayer games have two dimensions of rules that can be leveraged to improve player experiences - game rules that developers work with at the game design level and server rules that the player community creates and maintains. A few studies suggest that server rules can be leveraged to shape player experiences at the individual and community levels, but little work has investigated the role of server rules in play communities tailored for youth. The rise in online multiplayer gaming among youth motivates a need to understand how server rules shape the culture and climate of online communities. Using a mixed methods research approach, we analyzed server rules (1920) across 60 "in-the-wild" moderated Minecraft servers. We report on findings from a subset of 19 Minecraft servers explicitly tailored for young adolescents (475 rules). We offer a nuanced understanding of server rules in relation to youth developmental needs, particularly during early adolescence (ages 7-14 years) and discuss how server rules can be harnessed to shape positive player experiences in online gaming communities for all youth.
Communication Sequences Indicate Team Cohesion: A Mixed-Methods Study of Ad Hoc League of Legends Teams
Authors: Tan Evelyn T S , Rogers Katja , Nacke Lennart E. , Drachen Anders , Wade Alex
Published: October 2022

Team cohesion is a widely known predictor of performance and collaborative satisfaction. However, how it develops and can be assessed, especially in fast-paced ad hoc dynamic teams, remains unclear. An unobtrusive and objective behavioural measure of cohesion would help identify determinants of cohesion in these teams. We investigated team communication as a potential measure in a mixed-methods study with 48 teams (n=135) in the digital game League of Legends. We first established that cohesion shows similar performance and satisfaction in League of Legends. teams as in non-game teams and confirmed a positive relationship between communication word frequency and cohesion. Further, we conducted an in-depth exploratory qualitative analysis of the communication sequences in a high-cohesion and a low-cohesion team. High cohesion is associated with sequences of apology->encouragement, suggestion->agree/acknowledge, answer->answer, and answer->question, while low-cohesion is associated with sequences of opinion/analysis->opinion/analysis, disagree->disagree, command->disagree, and frustration->frustration. Our findings also show that cohesion is important to team satisfaction independently of the match outcomes. We highlight that communication sequences are more useful than frequencies to determine team cohesion via player interactions.
Daily Quests or Daily Pests? The Benefits and Pitfalls of Engagement Rewards in Games
Authors: Frommel Julian , Mandryk Regan L.
Published: October 2022

Many games use engagement rewards as incentives for players to engage, e.g., daily login rewards, repeatable challenges, or seasonal rewards like holiday skins. These rewards may serve players by facilitating enjoyment or motivation; however, they may also be considered differently by skeptical players, e.g., as dark patterns that do not benefit players, and may detract from-or even harm-player experiences. As they are widely prevalent in a variety of games, it is important to understand how such rewards are experienced by players to inform potential pitfalls, such as when they are negative for gaming experience or lead to unhealthy gaming behaviours. 178 participants completed a mixed-methods survey and described such rewards in games they play, the tasks required to acquire them, and their experience qualitatively and with validated scales of motivation regulation and passion orientation. We found that players perceived these rewards as beneficial (e.g., as motivation), as negative (e.g., by promoting fear of missing out), or even as an obligation or chore. Quantitative results further support the dualistic experience of such rewards. We contribute findings and design recommendations that are useful for understanding and designing widely used but potentially detrimental reward mechanics.
Don't Break my Flow: Effects of Switching Latency in Shooting Video Games
Authors: Halbhuber David , Schwind Valentin , Henze Niels
Published: October 2022

Latency is inherently part of every interactive computing system and particularly important for video games. Previous work shows that constant latency above 25 ms reduces game experience and player performance. However, latency in the wild varies and is never constant due to multiple factors, such as updates in routing tables, users changing their location, or the system's workload. It is unclear if switching latency impairs the gaming experience stronger than a constant high latency. To elucidate, we conducted an experiment with 264 participants playing a shooting video game induced with 0 ms, 33 ms, and 66 ms controlled latency. While playing, the game switched between different latency levels based on three frequencies. Our analysis shows that switching latency significantly impaired the participants' flow. Additionally, we found effects on the perceived tension, the experienced challenge, and the players' performance. We conclude that games should prioritize constant latency, even if that entails artificially adding latency.
Effects of PCG on Creativity in Playful City-Building Environments in VR
Authors: Volkmar Georg , Alexandrovsky Dmitry , Eilks Asmus Eike , Queck Dirk , Herrlich Marc , Malaka Rainer
Published: October 2022

The use of procedural content generation (PCG) in the context of video games has increased over the years as it provides an economical way to generate game content whilst enhancing their variety and replayability. For city-building games, this approach is often utilized to predefine map layouts, terrains, or cityscapes for the player. One core aspect of facilitating enjoyment in these games comes from creative expressivity. PCG, in this context, may support creativity by lowering the technical complexity for content creation, or it may hinder creativity by taking away control and freedom from the user. To examine these potential effects, this paper investigates if PCG has an impact on players' creativity in the context of VR city-building games. We present a VR prototype that provides varying degrees of procedural content: No PCG, terrain generation, city generation, and full (city + terrain) generation. In a remote user study, these conditions were compared regarding their capability to support creativity. Statistical tests for equivalence revealed that the presence of PCG did not affect creativity in any way. Our work suggests that PCG can be a useful integration into city-building games without notably decreasing players' ability to express themselves creatively.
LINA - A Social Augmented Reality Game around Mental Health, Supporting Real-world Connection and Sense of Belonging for Early Adolescents
Authors: Mittmann Gloria , Barnard Adam , Krammer Ina , Martins Diogo , Dias João
Published: October 2022

Early adolescence is a time of major social change; a strong sense of belonging (SB) and peer connectedness is an essential protective factor in mental health (MH) during that period. In this paper we introduce LINA, an augmented reality (AR) smartphone-based serious game played in school by an entire class (age 10+) together with their teacher, which aims to facilitate and improve peer interaction, SB and class climate, while creating a safe space to reflect on MH and external stressors related to family circumstance. LINA was developed through an interdisciplinary collaboration involving a playwright, software developers, psychologists and artists, via an iterative co-development process with young people. A prototype has been evaluated quantitatively for usability and qualitatively for efficacy in a study with 91 early adolescents (agemean=11.41). Results from the Game User Experience Satisfaction Scale (GUESS-18) and data from qualitative focus groups showed high acceptability and preliminary efficacy of the game. Using AR, a shared immersive narrative and collaborative gameplay in a shared physical space offers an opportunity to harness adolescent affinity for digital technology towards improving real-world social connection and SB.
Outpace Reality: A Novel Augmented-Walking Technique for Virtual Reality Games
Authors: Cmentowski Sebastian , Kievelitz Fabian , Krueger Jens Harald
Published: October 2022

The size of most virtual environments exceeds the tracking space available for physical walking. One solution to this disparity is to extend the available walking range by augmenting users' actual movements. However, the resulting increase in visual flow can easily cause cybersickness. Therefore, we present a novel augmented-walking approach for virtual reality games. Our core concept is a virtual tunnel that spans the entire travel distance when viewed from the outside. However, its interior is only a fraction as long, allowing users to cover the distance by real walking. Whereas the tunnel hides the visual flow from the applied movement acceleration, windows on the tunnel's walls still reveal the actual expedited motion. Our evaluation reveals that our approach avoids cybersickness while enhancing physical activity and preserving presence. We finish our paper with a discussion of the design considerations and limitations of our proposed locomotion technique.
Pay to Win or Pay to Cheat: How Players of Competitive Online Games Perceive Fairness of In-Game Purchases
Authors: Freeman Guo , Wu Karen , Nower Nicholas , Wohn Donghee Yvette
Published: October 2022

The advent of various in-game purchasing systems has led to several ethical concerns in contemporary gaming ecosystems, including the monetary dark patterns in game design and the potential harms on gamer welling by introducing cheating, gambling, and addictive mechanisms. These concerns have resulted in the rise of tensions regarding the impacts of in-game purchases on players who pay versus those who do not pay, such as their perceptions of "fairness" in highly competitive gaming contexts when spending is involved. Using 2,685 Reddit posts from five subreddits of popular online sports and card games that focus on player-to-player competition, we investigate how players of these games perceive fairness of their in-game purchases. This research expands our existing knowledge on ethical concerns and fairness in gaming by highlighting consumers' (players') diverse ethical judgments regarding the increasingly popular monetization mechanisms in modern gaming. It also highlights ethical dilemmas surrounding competition, spending, and enjoyment in online gaming and informs the design of future digital consumption systems for fairer, healthier, and more ethical gaming dynamics.
Persuasion Invasion: An Educational Game for Teaching Productive Civil Discourse Skills
Authors: Diana Nicholas
Published: October 2022

As civil discourse in America is becoming less substantive and respectful (Doherty et al., 2019), some educators have turned to educational games as a potential solution. However, due to the complexity the civic education space, games tend to focus on conceptual knowledge (e.g., the structure of government) rather than the practical skills students need to become productive and engaged citizens. Here we present Persuasion Invasion, an educational game that uses Value-Adaptive Instruction to help students learn to engage in productive civil discourse. Throughout the game, players learn about the values that underpin our beliefs and barriers to productive discourse (e.g., tribalism). Importantly, players also practice key civil discourse skills like identifying shared values across political lines and engaging in perspective taking. In this paper, we discuss the unique challenges of designing educational games in the civics domain, how we addressed those challenges, and how students responded to our design. Our results suggest that in-game practice was associated with improved learning outcomes on key discourse skill assessments. These results, coupled with qualitative student feedback, support the development of transformative and meaningful games in the civil discourse space.
Pokémon GO with Social Distancing: Social Media Analysis of Players' Experiences with Location-based Games
Authors: Saaty Morva , Haqq Derek , Beyki Mohammadreza , Hassan Taha , McCrickard D. Scott
Published: October 2022

Pokémon GO is a popular location-based mobile game that seeks to inspire players to be more active, socialize physically and virtually, and spend more time outside. With the onset of the COVID-19 pandemic, several game mechanics of Pokémon GO were changed to accommodate socially-distanced play. This research aims to understand the impacts of the pandemic and subsequent game adjustments on user perceptions of the game. We used an exploratory mixed-method approach, a machine learning technique (Latent Dirichlet Allocation) for topic modeling, and thematic analysis for qualitative coding of top-level Reddit comments to identify whether and how the social distancing approach changes the players' behaviors. The results demonstrate that players were less physically active, less eager to discover, and more interested in remote social practices. We discuss which players leverage social distancing changes and reflect on key game features that provide a better gaming experience in the age of remote play.
Tracking Stuffed Toy for Naturally Mapped Interactive Play via a Soft-Pose Estimator
Authors: Sin Zackary P. T. , Chen Peter Q. , Ng Peter H. F. , Leong Hong Va
Published: October 2022

Have you ever picked up a stuffed toy and pretended to play with it in your childhood? We are motivated by the novel use of stuffed toys in enhancing extended reality interaction. A key goal of extended reality is to induce the feeling of presence in its users. Naturally mapped control interface has been shown to enhance presence. The literature also indicates that a high degree of freedom tracking is important to extended reality. Based on these observations, we show that a free-form naturally mapped control interface is well-motivated via a theoretical contextualization. We explore the possibility of building such a controller in the form of stuffed toys. To realize stuffed toys as controllers, a novel soft-pose estimator empowered by cage-based deformation is proposed. It is shown to be effective in tracking the poses and deformations of real soft objects even by training with synthetic data only. Three gameplay prototypes are developed to demonstrate that interactive play can be enabled by the soft-pose estimator. They also form the basis for two user studies that validate the success of tracking stuffed toys with the soft-pose estimator for interactive play.
Values throughout the Game Space
Authors: Jerrett Adam , Howell Peter Mark
Published: October 2022

Pro-social themes like empathy and wellbeing are gaining popularity within games to contrast the medium's stigmatised explorations of themes like violence, often to catalyse reflection or even change players' beliefs surrounding complex scenarios. These abstract themes can be classified as a game's "values": elements that are "useful or important" to game designers and their audience.

Exploration of values in games was spearheaded by Values at Play, which described how values manifest in games and advocated for their explicit consideration within games and their discourse. Frameworks such as empathy, ethical, and anti-oppressive design all discuss similar values, but present ontological diversity that makes it difficult to collate games and frameworks under the values-conscious design umbrella. Such frameworks also often focus on design approaches and small-scale prototypes but pay less attention to how values influence aspects like publication and play. As such, the present research examines values within each stage of a game's lifecycle: design, development, publication, interaction, and reportage. Doing so provides an understanding of values in multiple game contexts. This provides new perspectives that form the basis of a taxonomy for values in games, which is then presented alongside practical questions for values-conscious designers, publishers, and players to guide its use.
AnICA: analyzing inconsistencies in microarchitectural code analyzers
Authors: Ritter Fabian , Hack Sebastian
Published: October 2022

Microarchitectural code analyzers, i.e., tools that estimate the throughput of
machine code basic blocks, are important utensils in the tool belt of
performance engineers. Recent tools like llvm-mca, uiCA, and Ithemal use a
variety of techniques and different models for their throughput predictions.
When put to the test, it is common to see these state-of-the-art tools give
very different results. These inconsistencies are either errors, or they point
to different and rarely documented assumptions made by the tool designers.

In this paper, we present AnICA, a tool taking inspiration from differential
testing and abstract interpretation to systematically analyze inconsistencies
among these code analyzers. Our evaluation shows that AnICA can summarize
thousands of inconsistencies in a few dozen descriptions that directly lead to
high-level insights into the different behavior of the tools. In several case
studies, we further demonstrate how AnICA automatically finds and characterizes
known and unknown bugs in llvm-mca, as well as a quirk in AMD's Zen
microarchitectures.
CAAT: consistency as a theory
Authors: Haas Thomas , Meyer Roland , Ponce de León Hernán
Published: October 2022

We propose a family of logical theories for capturing an abstract notion of consistency and show how to build a generic and efficient theory solver that works for all members in the family.
The theories can be used to model the influence of memory consistency models on the semantics of concurrent programs.
They are general enough to precisely capture important examples like TSO, POWER, ARMv8, RISC-V, RC11, IMM, and the Linux kernel memory model.
To evaluate the expressiveness of our theories and the performance of our solver, we integrate them into a lazy SMT scheme that we use as a backend for a bounded model checking tool.
An evaluation against related verification tools shows, besides flexibility, promising performance on challenging programs under complex memory models.
Reasoning about distributed reconfigurable systems
Authors: Ahrens Emma , Bozga Marius , Iosif Radu , Katoen Joost-Pieter
Published: October 2022

This paper presents a Hoare-style calculus for formal reasoning about
reconfiguration programs of distributed systems. Such programs create
and delete components and/or interactions (connectors) while the
system components change state according to their internal behaviour.
Our proof calculus uses a resource logic, in the spirit of Separation
Logic, to give local specifications of reconfiguration
actions. Moreover, distributed systems with an unbounded number of
components are described using inductively defined predicates. The
correctness of reconfiguration programs relies on havoc invariants,
that are assertions about the ongoing interactions in a part of the
system that is not affected by the structural change caused by the
reconfiguration. We present a proof system for such invariants in an
assume/rely-guarantee style. We illustrate the feasibility of our
approach by proving the correctness of real-life distributed systems
with reconfigurable (self-adjustable) tree architectures.
Scalable linear invariant generation with Farkas’ lemma
Authors: Liu Hongming , Fu Hongfei , Yu Zhiyong , Song Jiaxin , Li Guoqiang
Published: October 2022

Invariant generation is a classical problem to automatically generate invariants to aid the formal analysis of programs. In this work, we consider the problem of generating tight linear-invariants over affine programs (i.e., programs with affine guards and updates) without a prescribed goal property. In the literature, the only known sound and complete characterization to solve this problem is via Farkas’ Lemma (FL), and has been implemented through either quantifier elimination or reasonable heuristics. Although FL-based approaches can generate highly accurate linear invariants from the completeness of FL, the main bottleneck to applying these approaches is the scalability issue caused by either non-linear constraints or combinatorial explosion. We base our approach on the only practical FL-based approach [Sankaranarayanan ‍
et al.
, SAS 2004] that applies FL with reasonable heuristics, and develop two novel and independent improvements to leverage the scalability. The first improvement is the novel idea to generate invariants at one program location in a single invariant-generation process, so that the invariants for each location are generated separately rather than together in a single computation. This idea naturally leads to a parallel processing that divides the invariant-generation task for all program locations by assigning the locations separately to multiple processors. Moreover, the idea enables us to develop detailed technical improvements to further reduce the combinatorial explosion in the original work [Sankaranarayanan ‍
et al.
, SAS 2004]. The second improvement is a segmented subsumption testing in the CNF-to-DNF expansion that allows discovering more local subsumptions in advance. We formally prove that our approach has the same accuracy as the original work and thus does not incur accuracy loss on the generated invariants. Moreover, experimental results on representative benchmarks involving non-trivial linear invariants demonstrate that our approach improves the runtime of the original work by several orders of magnitude, even in the non-parallel scenario that sums up the execution time for all program locations. Hence, our approach constitutes the first significant improvement in FL-based approaches for linear invariant generation after almost two decades.
Can guided decomposition help end-users write larger block-based programs? a mobile robot experiment
Authors: Ritschel Nico , Fronchetti Felipe , Holmes Reid , Garcia Ronald , Shepherd David C.
Published: October 2022

Block-based programming environments, already popular in computer science education, have been successfully used to make programming accessible to end-users in domains like robotics, mobile apps, and even DevOps. Most studies of these applications have examined small programs that fit within a single screen, yet real-world programs often grow large, and editing these large block-based programs quickly becomes unwieldy. Traditional programming language features, like functions, allow programmers to decompose their programs. Unfortunately, both previous work, and our own findings, suggest that end-users rarely use these features, resulting in large monolithic code blocks that are hard to understand. In this work, we introduce a block-based system that provides users with a hierarchical, domain-specific program structure and requires them to decompose their programs accordingly. Through a user study with 92 users, we compared this approach, which we call guided program decomposition, to a traditional system that supports functions, but does not require decomposition. We found that while almost all users could successfully complete smaller tasks, those who decomposed their programs were significantly more successful as the tasks grew larger. As expected, most users without guided decomposition did not decompose their programs, resulting in poor performance on larger problems. In comparison, users of guided decomposition performed significantly better on the same tasks. Though this study investigated only a limited selection of tasks in one specific domain, it suggests that guided decomposition can benefit end-user programmers. While no single decomposition strategy fits all domains, we believe that similar domain-specific sub-hierarchies could be found for other application areas, increasing the scale of code end-users can create and understand.
Concurrent size
Authors: Sela Gal , Petrank Erez
Published: October 2022

The size of a data structure (i.e., the number of elements in it) is a widely used property of a data set. However, for concurrent programs, obtaining a correct size efficiently is non-trivial. In fact, the literature does not offer a mechanism to obtain a correct (linearizable) size of a concurrent data set without resorting to inefficient solutions, such as taking a full snapshot of the data structure to count the elements, or acquiring one global lock in all update and size operations. This paper presents a methodology for adding a concurrent linearizable size operation to sets and dictionaries with a relatively low performance overhead. Theoretically, the proposed size operation is wait-free with asymptotic complexity linear in the number of threads (independently of data-structure size). Practically, we evaluated the performance overhead by adding size to various concurrent data structures in Java−a skip list, a hash table and a tree. The proposed linearizable size operation executes faster by orders of magnitude compared to the existing option of taking a snapshot, while incurring a throughput loss of 1%−20% on the original data structure’s operations.
Incremental type-checking for free: using scope graphs to derive incremental type-checkers
Authors: Zwaan Aron , van Antwerpen Hendrik , Visser Eelco
Published: October 2022

Fast analysis response times in IDEs are essential for a good editor experience.
Incremental type-checking can provide that in a scalable fashion.
However, existing techniques are not reusable between languages.
Moreover, mutual and dynamic dependencies preclude traditional approaches to incrementality.
This makes finding automatic approaches to incremental type-checking a challenging but important open question.

In this paper, we present a technique that automatically derives incremental type-checkers from type system specifications written in the Statix meta-DSL.
We use name resolution queries in scope graphs (a generic model of name binding embedded in Statix) to derive dependencies between compilation units.
A novel query confirmation algorithm finds queries for which the answer changed due to an edit in the program.
Only units with such queries require reanalysis.
The effectiveness of this algorithm is improved by
(1) splitting the type-checking task into a context-free and a context-sensitive part, and
(2) reusing a generic mechanism to resolve mutual dependencies.
This automatically yields incremental type-checkers for any Statix specification.

Compared to non-incremental parallel execution, we achieve speedups up to 147x on synthetic benchmarks, and up to 21x on real-world projects, with initial overheads below 10%.
This suggests that our framework can provide efficient incremental type-checking to the wide range of languages supported by Statix.
Type-directed synthesis of visualizations from natural language queries
Authors: Chen Qiaochu , Pailoor Shankara , Barnaby Celeste , Criswell Abby , Wang Chenglong , Durrett Greg , Dillig Işil
Published: October 2022

We propose a new technique based on program synthesis for automatically generating visualizations from natural language queries. Our method parses the natural language query into a refinement type specification using the intents-and-slots paradigm and leverages type-directed synthesis to generate a set of visualization programs that are most likely to meet the user's intent. Our refinement type system captures useful hints present in the natural language query and allows the synthesis algorithm to reject visualizations that violate well-established design guidelines for the input data set. We have implemented our ideas in a tool called Graphy and evaluated it on NLVCorpus, which consists of 3 popular datasets and over 700 real-world natural language queries. Our experiments show that Graphy significantly outperforms state-of-the-art natural language based visualization tools, including transformer and rule-based ones.
Coeffects for sharing and mutation
Authors: Bianchini Riccardo , Dagnino Francesco , Giannini Paola , Zucca Elena , Servetto Marco
Published: October 2022

In
type-and-coeffect systems
, contexts are enriched by
coeffects
modeling how they are actually used, typically through annotations on single variables. Coeffects are computed bottom-up, combining, for each term, the coeffects of its subterms, through a fixed set of algebraic operators. We show that this principled approach can be adopted to track
sharing
in the imperative paradigm, that is, links among variables possibly introduced by the execution. This provides a significant example of non-structural coeffects, which cannot be computed by-variable, since the way a given variable is used can affect the coeffects of other variables. To illustrate the effectiveness of the approach, we enhance the type system tracking sharing to model a sophisticated set of features related to uniqueness and immutability. Thanks to the coeffect-based approach, we can express such features in a simple way and prove related properties with standard techniques.
A general construction for abstract interpretation of higher-order automatic differentiation
Authors: Laurel Jacob , Yang Rem , Ugare Shubham , Nagel Robert , Singh Gagandeep , Misailovic Sasa
Published: October 2022

We present a novel, general construction to abstractly interpret higher-order automatic differentiation (AD). Our construction allows one to instantiate an abstract interpreter for computing derivatives up to a chosen order. Furthermore, since our construction reduces the problem of abstractly reasoning about derivatives to abstractly reasoning about real-valued straight-line programs, it can be instantiated with almost any numerical abstract domain, both relational and non-relational. We formally establish the soundness of this construction.

We implement our technique by instantiating our construction with both the non-relational interval domain and the relational zonotope domain to compute both first and higher-order derivatives. In the latter case, we are the first to apply a relational domain to automatic differentiation for abstracting higher-order derivatives, and hence we are also the first abstract interpretation work to track correlations across not only different variables, but different orders of derivatives.

We evaluate these instantiations on multiple case studies, namely robustly explaining a neural network and more precisely computing a neural network’s Lipschitz constant. For robust interpretation, first and second derivatives computed via zonotope AD are up to 4.76× and 6.98× more precise, respectively, compared to interval AD. For Lipschitz certification, we obtain bounds that are up to 11,850× more precise with zonotopes, compared to the state-of-the-art interval-based tool.
Satisfiability modulo fuzzing: a synergistic combination of SMT solving and fuzzing
Authors: Muduli Sujit Kumar , Roy Subhajit
Published: October 2022

Programming languages and software engineering tools routinely encounter components that are difficult to reason on via formal techniques or whose formal semantics are not even available—third-party libraries, inline assembly code, SIMD instructions, system calls, calls to machine learning models, etc. However, often access to these components is available as input-output oracles—interfaces are available to query these components on certain inputs to receive the respective outputs. We refer to such functions as
closed-box functions
. Regular SMT solvers are unable to handle such closed-box functions.

We propose Sādhak, a solver for SMT theories modulo closed-box functions. Our core idea is to use a synergistic combination of a fuzzer to reason on closed-box functions and an SMT engine to solve the constraints pertaining to the SMT theories. The fuzz and the SMT engines attempt to converge to a model by exchanging a rich set of
interface constraints
that are relevant and interpretable by them. Our implementation, Sādhak, demonstrates a significant advantage over the only other solver that is capable of handling such closed-box constraints: Sādhak solves 36.45% more benchmarks than the best-performing mode of this state-of-the-art solver and has 5.72x better PAR-2 score; on the benchmarks that are solved by both tools, Sādhak is (on an average) 14.62x faster.
Synthesizing abstract transformers
Authors: Kalita Pankaj Kumar , Muduli Sujit Kumar , D’Antoni Loris , Reps Thomas , Roy Subhajit
Published: October 2022

This paper addresses the problem of creating abstract transformers automatically. The method we present automates the construction of static analyzers in a fashion similar to the way
yacc
automates the construction of parsers. Our method treats the problem as a program-synthesis problem. The user provides specifications of (i) the concrete semantics of a given operation
op
, (ii) the abstract domain
A
to be used by the analyzer, and (iii) the semantics of a domain-specific language
L
in which the abstract transformer is to be expressed. As output, our method creates an abstract transformer for
op
in abstract domain
A
, expressed in
L
(an “
L
-transformer for
op
over
A
”). Moreover, the abstract transformer obtained is a most-precise
L
-transformer for
op
over
A
; that is, there is no other
L
-transformer for
op
over
A
that is strictly more precise.

We implemented our method in a tool called AMURTH. We used AMURTH to create sets of replacement abstract transformers for those used in two existing analyzers, and obtained essentially identical performance. However, when we compared the existing transformers with the transformers obtained using AMURTH, we discovered that four of the existing transformers were unsound, which demonstrates the risk of using manually created transformers.
Checking equivalence in a non-strict language
Authors: Kolesar John C. , Piskac Ruzica , Hallahan William T.
Published: October 2022

Program equivalence checking is the task of confirming that two programs have the same behavior on corresponding inputs. We develop a calculus based on symbolic execution and coinduction to check the equivalence of programs in a non-strict functional language. Additionally, we show that our calculus can be used to derive counterexamples for pairs of inequivalent programs, including counterexamples that arise from non-termination. We describe a fully automated approach for finding both equivalence proofs and counterexamples. Our implementation, Nebula, proves equivalences of programs written in Haskell. We demonstrate Nebula's practical effectiveness at both proving equivalence and producing counterexamples automatically by applying Nebula to existing benchmark properties.