567 research outputs found
Language Design for Reactive Systems: On Modal Models, Time, and Object Orientation in Lingua Franca and SCCharts
Reactive systems play a crucial role in the embedded domain. They continuously interact with their environment, handle concurrent operations, and are commonly expected to provide deterministic behavior to enable application in safety-critical systems. In this context, language design is a key aspect, since carefully tailored language constructs can aid in addressing the challenges faced in this domain, as illustrated by the various concurrency models that prevent the known pitfalls of regular threads. Today, many languages exist in this domain and often provide unique characteristics that make them specifically fit for certain use cases. This thesis evolves around two distinctive languages: the actor-oriented polyglot coordination language Lingua Franca and the synchronous statecharts dialect SCCharts. While they take different approaches in providing reactive modeling capabilities, they share clear similarities in their semantics and complement each other in design principles. This thesis analyzes and compares key design aspects in the context of these two languages. For three particularly relevant concepts, it provides and evaluates lean and seamless language extensions that are carefully aligned with the fundamental principles of the underlying language. Specifically, Lingua Franca is extended toward coordinating modal behavior, while SCCharts receives a timed automaton notation with an efficient execution model using dynamic ticks and an extension toward the object-oriented modeling paradigm
Language integrated relational lenses
Relational databases are ubiquitous. Such monolithic databases accumulate large
amounts of data, yet applications typically only work on small portions of the data
at a time. A subset of the database defined as a computation on the underlying
tables is called a view. Querying views is helpful, but it is also desirable to update
them and have these changes be applied to the underlying database. This view
update problem has been the subject of much previous work before, but support
by database servers is limited and only rarely available.
Lenses are a popular approach to bidirectional transformations, a generalization
of the view update problem in databases to arbitrary data. However, perhaps surprisingly, lenses have seldom actually been used to implement updatable views in
databases. Bohannon, Pierce and Vaughan propose an approach to updatable views called relational lenses. However, to the best of our knowledge this
proposal has not been implemented or evaluated prior to the work reported in
this thesis.
This thesis proposes programming language support for relational lenses. Language integrated relational lenses support expressive and efficient view updates,
without relying on updatable view support from the database server. By integrating relational lenses into the programming language, application development
becomes easier and less error-prone, avoiding the impedance mismatch of having
two programming languages. Integrating relational lenses into the language poses
additional challenges. As defined by Bohannon et al. relational lenses completely
recompute the database, making them inefficient as the database scales. The
other challenge is that some parts of the well-formedness conditions are too general for implementation. Bohannon et al. specify predicates using possibly infinite
abstract sets and define the type checking rules using relational algebra.
Incremental relational lenses equip relational lenses with change-propagating semantics that map small changes to the view into (potentially) small changes
to the source tables. We prove that our incremental semantics are functionally
equivalent to the non-incremental semantics, and our experimental results show
orders of magnitude improvement over the non-incremental approach. This thesis introduces a concrete predicate syntax and shows how the required checks
are performed on these predicates and show that they satisfy the abstract predicate specifications. We discuss trade-offs between static predicates that are fully
known at compile time vs dynamic predicates that are only known during execution and introduce hybrid predicates taking inspiration from both approaches.
This thesis adapts the typing rules for relational lenses from sequential composition to a functional style of sub-expressions. We prove that any well-typed
functional relational lens expression can derive a well-typed sequential lens.
We use these additions to relational lenses as the foundation for two practical implementations: an extension of the Links functional language and a library written
in Haskell. The second implementation demonstrates how type-level computation can be used to implement relational lenses without changes to the compiler.
These two implementations attest to the possibility of turning relational lenses
into a practical language feature
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Phase transition in Random Circuit Sampling
Quantum computers hold the promise of executing tasks beyond the capability
of classical computers. Noise competes with coherent evolution and destroys
long-range correlations, making it an outstanding challenge to fully leverage
the computation power of near-term quantum processors. We report Random Circuit
Sampling (RCS) experiments where we identify distinct phases driven by the
interplay between quantum dynamics and noise. Using cross-entropy benchmarking,
we observe phase boundaries which can define the computational complexity of
noisy quantum evolution. We conclude by presenting an RCS experiment with 70
qubits at 24 cycles. We estimate the computational cost against improved
classical methods and demonstrate that our experiment is beyond the
capabilities of existing classical supercomputers
Resilient and Scalable Forwarding for Software-Defined Networks with P4-Programmable Switches
Traditional networking devices support only fixed features and limited configurability.
Network softwarization leverages programmable software and hardware platforms to remove those limitations.
In this context the concept of programmable data planes allows directly to program the packet processing pipeline of networking devices and create custom control plane algorithms.
This flexibility enables the design of novel networking mechanisms where the status quo struggles to meet high demands of next-generation networks like 5G, Internet of Things, cloud computing, and industry 4.0.
P4 is the most popular technology to implement programmable data planes.
However, programmable data planes, and in particular, the P4 technology, emerged only recently.
Thus, P4 support for some well-established networking concepts is still lacking and several issues remain unsolved due to the different characteristics of programmable data planes in comparison to traditional networking.
The research of this thesis focuses on two open issues of programmable data planes.
First, it develops resilient and efficient forwarding mechanisms for the P4 data plane as there are no satisfying state of the art best practices yet.
Second, it enables BIER in high-performance P4 data planes.
BIER is a novel, scalable, and efficient transport mechanism for IP multicast traffic which has only very limited support of high-performance forwarding platforms yet.
The main results of this thesis are published as 8 peer-reviewed and one post-publication peer-reviewed publication. The results cover the development of suitable resilience mechanisms for P4 data planes, the development and implementation of resilient BIER forwarding in P4, and the extensive evaluations of all developed and implemented mechanisms. Furthermore, the results contain a comprehensive P4 literature study.
Two more peer-reviewed papers contain additional content that is not directly related to the main results.
They implement congestion avoidance mechanisms in P4 and develop a scheduling concept to find cost-optimized load schedules based on day-ahead forecasts
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Sonic heritage: listening to the past
History is so often told through objects, images and photographs, but the potential of sounds to reveal place and space is often neglected. Our research project ‘Sonic Palimpsest’1 explores the potential of sound to evoke impressions and new understandings of the past, to embrace the sonic as a tool to understand what was, in a way that can complement and add to our predominant visual understandings. Our work includes the expansion of the Oral History archives held at Chatham Dockyard to include women’s voices and experiences, and the creation of sonic works to engage the public with their heritage. Our research highlights the social and cultural value of oral history and field recordings in the transmission of knowledge to both researchers and the public. Together these recordings document how buildings and spaces within the dockyard were used and experienced by those who worked there. We can begin to understand the social and cultural roles of these buildings within the community, both past and present
Exploring the Harm Reduction Potential of Cashless Gambling Payment Systems for Electronic Gaming Machines
Consumers are increasingly using cashless payments for everyday retail purchases. Despite this
trend, cash use remains the status quo in physical gambling environments. The accessibility of
money plays an important role in regulating gambling behaviour, but little prior literature directly
addresses the relative utility of cash and cashless payments for controlling spending. Excessive
spending on gambling can have harmful consequences. Focusing on electronic gaming machine
(EGM) gambling in Australia, this thesis presents three studies exploring potential impacts of
transitioning to cashless payment systems on gambling behaviour and harm, and the optimal design
and implementation of such systems for effective harm reduction. In the first study, a meta-analytic
review of 94 studies from broader literature on consumer behaviour finds that cashless payments
have a small effect in encouraging spending relative to cash use in retail settings. Over more than four decades studied, this effect appears not to have changed in size. In the second study, a
qualitative analysis of focus group discussions suggests regular EGM gamblers perceive accountbased
cashless systems to present opportunities for stronger harm reduction measures by tracking
individuals’ gambling activity. Concerns about excessive restrictions, privacy, and overspending are
identified as potential barriers to uptake of a voluntary system. In the final study, a discrete choice
analysis of hypothetical systems with varying harm reduction potential shows that regular EGM
gamblers most prefer a smartphone-based system that operates across multiple venues, involves
mandatory self-imposed limits, and is linked with loyalty schemes. Modelling suggests at least
42.5%–62.9% of regular EGM gamblers would not opt-in to a voluntary cashless system. Overall,
findings provide support for a mandatory cashless system with strong harm reduction features,
including requirements for gamblers to set personalised loss limits
Lattice-Based SNARKs: Publicly Verifiable, Preprocessing, and Recursively Composable
A succinct non-interactive argument of knowledge (SNARK) allows a prover to produce a short proof that certifies the veracity of a certain NP-statement. In the last decade, a large body of work has studied candidate constructions that are secure against quantum attackers. Unfortunately, no known candidate matches the efficiency and desirable features of (pre-quantum) constructions based on bilinear pairings.
In this work, we make progress on this question. We propose the first lattice-based SNARK that simultaneously satisfies many desirable properties: It (i) is tentatively post-quantum secure, (ii) is publicly-verifiable, (iii) has a logarithmic-time verifier and (iv) has a purely algebraic structure making it amenable to efficient recursive composition. Our construction stems from a general technical toolkit that we develop to translate pairing-based schemes to lattice-based ones. At the heart of our SNARK is a new lattice-based vector commitment (VC) scheme supporting openings to constant-degree multivariate polynomial maps, which is a candidate solution for the open problem of constructing VC schemes with openings to beyond linear functions. However, the security of our constructions is based on a new family of lattice-based computational assumptions which naturally generalises the standard Short Integer Solution (SIS) assumption
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
METROPOLITAN ENCHANTMENT AND DISENCHANTMENT. METROPOLITAN ANTHROPOLOGY FOR THE CONTEMPORARY LIVING MAP CONSTRUCTION
We can no longer interpret the contemporary metropolis as we did in the last century. The thought of civil economy regarding the contemporary Metropolis conflicts more or less radically with the merely acquisitive dimension of the behaviour of its citizens. What is needed is therefore a new capacity for
imagining the economic-productive future of the city: hybrid social enterprises, economically sustainable, structured and capable of using technologies, could be a solution for producing value and distributing it fairly and inclusively.
Metropolitan Urbanity is another issue to establish. Metropolis needs new spaces where inclusion can occur, and where a repository of the imagery can be recreated. What is the ontology behind the technique of metropolitan planning and management, its vision and its symbols? Competitiveness,
speed, and meritocracy are political words, not technical ones. Metropolitan Urbanity is the characteristic of a polis that expresses itself in its public places. Today, however, public places are private ones that are destined for public use. The Common Good has always had a space of representation in the city, which was the public space. Today, the Green-Grey Infrastructure is the metropolitan city's monument that communicates a value for future generations and must therefore be recognised and imagined; it is the production of the metropolitan symbolic imagery, the new magic of the city
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