The post Logic Seminar talk: VLSM appeared first on Institute for Logic and Data Science.

]]>**Title**: VLSM: A General Framework for Reasoning About Faulty Distributed Systems

**Abstract**:

Formally modeling and reasoning about distributed systems with faults is a challenging task [1]. Depending on the system model, an execution of a distributed protocol may be subject to many kinds of faults, from simple recoverable component crashes to Byzantine adversarial actions [4]. Each kind of failure may then require specific actions for evasion or recovery by the affected components.

To address this problem, we recently proposed the theory of *Validating Labeled State transition and Message production systems (VLSMs)* as a general approach to modeling and verifying distributed protocols executing in the presence of faults [5]. In particular, VLSM executions can be subject to *equivocation behavior*. Equivocation refers to claiming different beliefs about the state of the protocol to different parts of the system in order to steer the protocol-following components into making inconsistent decisions; messages received from equivocating components seem to be valid messages [3]. For example, if a system tries to come to a consensus about the value of a bit, an equivocating component may claim the bit is 0 to one part of the system, and 1 to the other. Equivocation behavior cannot be produced by a single protocol execution, but only by multiple protocol executions, i.e., an equivocating component behaves as if running multiple copies of the protocol.

Our VLSM-based modeling and verification methodology for distributed protocols follows the *correct-by-construction* approach for design and development [2]: we define an abstract class of protocols (satisfying some generic abstract properties), prove general results about protocols belonging to the class, and then obtain correct-by-construction protocols by concretely instantiating the abstract components, or, alternatively, prove that concrete protocols satisfy those requirements.

**References**:

[1] Pedro Fonseca, Kaiyuan Zhang, Xi Wang & Arvind Krishnamurthy (2017): An Empirical Study on the Correctness of Formally Verified Distributed Systems. In: *European Conference on Computer Systems*, pp. 328–343, doi:10.1145/3064176.3064183.

[2] David Gries (1981): *The Science of Programming*. Springer, doi:10.1007/978-1-4612-5983-1.

[3] Alexander Jaffe, Thomas Moscibroda & Siddhartha Sen (2012): On the price of equivocation in Byzantine agreement. In: *Symposium on Principles of Distributed Computing*, pp. 309–318, doi:10.1145/2332432.2332491.

[4] Leslie Lamport, Robert Shostak & Marshall Pease (1982): The Byzantine Generals Problem. *ACM Transactions on Programming Languages and Systems* 4(3), pp. 382–401, doi:10.1145/357172.357176.

[5] V. Zamfir, M. Calancea, D. Diaconescu, W. Kołowski, B. Moore, K. Palmskog, T. F. Șerbănuță, M. Stay, D. Trufaș, & J. Tušil (2022): Validating Labelled State Transition and Message Production Systems: A Theory for Modelling Faulty Distributed Systems. arXiv:2202.12662 [cs.DC].

The talk will take place physically at FMI (Academiei 14), Hall 214 “Google”.

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]]>The post Blockchain Seminar talk: Testing blockchains – a survey of state of the art (Part I) appeared first on Institute for Logic and Data Science.

]]>**Title**: Testing blockchains – a survey of state of the art (Part I)

**Abstract**: The blockchain technology is continuously extending to various domains and use cases which would benefit of the by-design features of the paradigm such as decentralization, immutability, implementation of complex business logic and processes through smart contracts. As this happens, it is important that blockchain-based applications’ testing and assessment methods be considered and developed to detect bugs and vulnerabilities. The testing of this new type of application presents specific challenges that the research in the field had to consider, as they are different from other application types, the nodes are decentralized, and the smart contracts are developed in relatively recent programming languages. Also, testing blockchains may cover different testing areas, which might refer to components or performance testing. We present a survey of the state-of-the-art of the field, highlighting the challenges in this particular type of applications, the existing solutions on different testing areas and the directions which need the attention of the testing community.

The talk will take place physically at the Faculty of Mathematics and Computer Science (Academiei 14; Hall 214 “Google”), and also remotely (via Microsoft Teams).

The post Blockchain Seminar talk: Testing blockchains – a survey of state of the art (Part I) appeared first on Institute for Logic and Data Science.

]]>The post Logic Seminar talk: Zero-knowledge proofs appeared first on Institute for Logic and Data Science.

]]>**Title**: Zero-knowledge proofs

**Abstract**: We introduce the notion of zero-knowledge proof and some of its realizations in graphs and in sigma-protocols. Also, some applications in logic and in other cryptographic protocols are presented.

The talk will take place physically at FMI (Academiei 14), Hall 214 “Google”.

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]]>The post Data Science Seminar talk: Continuous, Gradual Entity Mining from Web Data Streams appeared first on Institute for Logic and Data Science.

]]>**Title**: Continuous, Gradual Entity Mining from Web Data Streams

**Abstract**: Named Entity Recognition (NER) is a key component in many intelligent systems like knowledge graphs, question answering, information retrieval, and early prediction of emerging events. NER systems have been studied and developed for decades, nevertheless NER is a continuous, neverending learning process because language and its usage evolves over time. For example, the emergence of social media with colloquial user content exposed the previous state-of-the-art NER that expected long documents written in formal language. In this talk, I present our work on entity mining from microblog streams, where we advocate for continuous, gradual entity mining with revisits. It needs to be continuous because the system stays with a topic for its duration in a social media stream. It is gradual because the system begins with easy instances, which can be labeled with high accuracy, and then it gradually labels more challenging instances. The system revisits difficult instances that were encountered ahead of easy instances in a stream. If these three conditions are met than (near) real-time NER can be achieved over microblogs. I will also introduce our work on recognizing entities that follow or closely resemble a regular expression (regex) pattern, their applications to other (unexpected) domains, and how we use it to seed our work on human-in-the-loop mining.

The talk will take place physically at FMI (Academiei 14), Hall 214 “Google”.

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]]>The post RV/ILDS Blockchain Workshop appeared first on Institute for Logic and Data Science.

]]>The event will be held physically (and broadcast online on the Google Meet). Participation is free, but we have a limited number of places available, so please register by sending an email to blockchain2023@ilds.ro.

For more information, check out the workshop website.

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]]>The post Logic Seminar talk: Implementing Program Verification in the 𝕂 Framework appeared first on Institute for Logic and Data Science.

]]>**Title**: Implementing Program Verification in the 𝕂 Framework

**Abstract**: In this talk we will briefly introduce 𝕂, a rewriting-based framework for defining programming languages semantics, discuss Reachability Logic, the language-agnostic program verification logic for 𝕂, and give some hints about the current implementation.

The talk will take place physically at FMI Hall 214 “Google”.

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]]>The post Logic Seminar talk: Semantics for Quantified Modal Logics appeared first on Institute for Logic and Data Science.

]]>**Title**: Semantics for Quantified Modal Logics

**Abstract**: The talk presents several semantics for quantified modal logics: standard semantics, constant domains and possibilist quantifiers, weak necessity and truth-value gaps, semantics for “actually”, Kit Fine on the de re / de dicto distinction, and counterpart theory (David Lewis and Graeme Forbes styles, respectively). I shall also discuss some philosophical issues surrounding the formal semantics for quantified modal logics.

The talk will take place physically at FMI Hall 214 “Google”.

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]]>The post Logic Seminar talk: A short guide to implementing theorem provers appeared first on Institute for Logic and Data Science.

]]>**Title**: A short guide to implementing theorem provers

**Abstract**: We briefly venture into the world of experimental theorem proving to see what it takes to bring proof calculi to life, making them readily available for teaching and for further research purposes. In contrast to many mainstream theorem provers such as E, Vampire, Gandalf, Isabelle, or Lean, which are based on some specific logics (or families of logics), the approach we propose here is generic. That is, we separate those aspects of a theorem prover that are language independent (e.g., basic proof management) from aspects that are language dependent, such as the base logical system(s) or the kind of inference rules used in proofs. Our effort is supported by SpeX, a rewrite-based environment that facilitates the development of formal-specification languages and tools.

The talk will take place physically at FMI Hall 214 “Google”.

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]]>The post Blockchain Seminar talk: A Method for Secure Generation, Exchange and Management of a User Identity Data using a Blockchain appeared first on Institute for Logic and Data Science.

]]>**Title**: A Method for Secure Generation, Exchange and Management of a User Identity Data using a Blockchain

**Abstract**: In this presentation we discuss the solution presented in the European Patent no. EP3883294A1 in regards to the self-sovereign problem. The patent presents a software application based on a public distributed ledger stored on a blockchain, with several users with different attributes interacting on a unsecured network. Although the main application of the product described in the patent is a self-sovereign identity scheme that can be used by government institutions and businesses alike, it also can allow autonomous devices to prove to third parties that they are allowed to perform certain tasks.

The talk will take place physically at the Faculty of Mathematics and Computer Science (Academiei 14; Hall 214 “Google”), and also remotely (via Microsoft Teams).

The post Blockchain Seminar talk: A Method for Secure Generation, Exchange and Management of a User Identity Data using a Blockchain appeared first on Institute for Logic and Data Science.

]]>The post Project in collaboration with arGO: Machine Learning Techniques for Computer Numerical Control Machines appeared first on Institute for Logic and Data Science.

]]>For more information, see the project page.

The post Project in collaboration with arGO: Machine Learning Techniques for Computer Numerical Control Machines appeared first on Institute for Logic and Data Science.

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