arXiv subjects

Karen Rudie

Publications and source records attributed to Karen Rudie.

10 recordsLinked to original sources

arXiv2026

A Case Study in Recovery of Drones using Discrete-Event Systems

Discrete-event systems and supervisory control theory provide a rigorous framework for specifying correct-by-construction behavior. However, their practical application to swarm robotics remains largely underexplored. In this paper, we investigate a topological recovery method based on discrete-event-systems within a swarm robotics context. We propose a hybrid architecture that combines a high-level discrete event systems supervisor with a low-level continuous controller, allowing lost drones to safely recover from fault or attack events and re-enter a controlled region. The method is demonstrated using ten simulated UAVs in the py-bullet-drones framework. We show recovery performance across four distinct scenarios, each with varying initial state estimates. Additionally, we introduce a secondary recovery supervisor that manages the regrouping process for a drone after it has re-entered the operational region.

eess.SY↗

arXiv2024

Collaboration or Corporate Capture? Quantifying NLP's Reliance on Industry Artifacts and Contributions

Impressive performance of pre-trained models has garnered public attention and made news headlines in recent years. Almost always, these models are produced by or in collaboration with industry. Using them is critical for competing on natural language processing (NLP) benchmarks and correspondingly to stay relevant in NLP research. We surveyed 100 papers published at EMNLP 2022 to determine the degree to which researchers rely on industry models, other artifacts, and contributions to publish in prestigious NLP venues and found that the ratio of their citation is at least three times greater than what would be expected. Our work serves as a scaffold to enable future researchers to more accurately address whether: 1) Collaboration with industry is still collaboration in the absence of an alternative or 2) if NLP inquiry has been captured by the motivations and research direction of private corporations.

cs.CL↗

arXiv2024

Distributed Secret Securing in Discrete-Event Systems

In this paper, we study a security problem of protecting secrets in distributed systems. Specifically, we employ discrete-event systems to describe the structure and behaviour of distributed systems, in which global secret information is separated into pieces and stored in local component agents. The goal is to prevent such secrets from being exposed to intruders by imposing appropriate protection measures. This problem is formulated as to ensure that at least one piece of every distributed global secret is secured by a required number of protections, while the overall cost to apply protections is minimum. We first characterize the solvability of this security problem by providing a necessary and sufficient condition, and then develop an algorithm to compute a solution based on the supervisory control theory of discrete-event systems. Finally, we illustrate the effectiveness of our solution with an example system comprising distributed databases.

eess.SY↗

arXiv2023

A Uniform Approach to Compare Architectures in Decentralized Discrete-Event Systems

Solutions to decentralized discrete-event systems problems are characterized by the way local decisions are fused to yield a global decision. A fusion rule is colloquially called an architecture. Current approaches do not provide a direct way to compare existing architectures. Determining whether an architecture is more permissive than another architecture had relied on producing examples ad hoc and on individual inspiration that puts the conditions for solvability in each architecture into some form that admits comparison. In response to these research efforts, a method based on morphisms between graphs has been extracted to yield a uniform approach to compare the permissiveness of the architectures.

eess.SY↗

arXiv2023

Equivalence of Decentralized Observation, Diagnosis, and Control Problems in Discrete-event Systems

This paper demonstrates an equivalence between observation problems, control problems (with partial observation), and diagnosis problems of decentralized discrete-event systems, namely, the three classes of problems are Turing equivalent, as one class Turing reduces to another. The equivalence allows decomposition of a control problem into a collection of simpler control sub\-/problems, which are each equivalent to an observation problem; and similarly allows converting a diagnosis problem to a formally simpler observation problem. Since observation problems in their most general formulation have been shown to be undecidable in previous work, the equivalence produced here demonstrates that control problems are also undecidable; whereas the undecidability of diagnosis problems is a known result.

eess.SY↗

arXiv2022

Using Subobservers to Synthesize Opacity-Enforcing Supervisors

In discrete-event system control, the worst-case time complexity for computing a system's observer is exponential in the number of that system's states. This results in practical difficulties since some problems require calculating multiple observers for a changing system, e.g., synthesizing an opacity-enforcing supervisor. Although calculating these observers in an iterative manner allows us to synthesize an opacity-enforcing supervisor and although methods have been proposed to reduce the computational demands, room exists for a practical and intuitive solution. Here we extend the subautomaton relationship to the notion of a subobserver and demonstrate its use in reducing the computations required for iterated observer calculations. We then demonstrate the subobserver relationship's power by simplifying state-of-the-art synthesis approaches for opacity-enforcing supervisors under realistic assumptions.

eess.SY↗

arXiv2022

Do What You Know: Coupling Knowledge with Action in Discrete-Event Systems

An epistemic model for decentralized discrete-event systems with non-binary control is presented. This framework combines existing work on conditional control decisions with existing work on formal reasoning about knowledge in discrete-event systems. The novelty in the model presented is that the necessary and sufficient conditions for problem solvability encapsulate the actions that supervisors must take. This direct coupling between knowledge and action -- in a formalism that mimics natural language -- makes it easier, when the problem conditions fail, to determine how the problem requirements should be revised.

cs.AI↗

arXiv2022

A Framework for the High-Level Specification and Verification of Synchronous Digital Logic Systems

A syntactic model is presented for the specification of finite-state synchronous digital logic systems with complex input/output interfaces, which control the flow of data between opaque computational elements, and for the composition of compatible systems to form closed-loop systems with no inputs or outputs. This model improves upon similar existing models with a novel approach to specifying input and output ports in a way which is uniform and symmetric. An automaton model is also presented for encoding arbitrary computational processes, and an algorithm is presented to generate an automaton representation of a closed-loop system. Using the automaton model, the problem of timing-agnostic verification of closed-loop systems against a desired behavioural specification, encoded as the similarity of closed-loop systems in terms of the set of computations performed, is shown to be decidable. The relationship between the models and real-world implementations of systems is discussed.

cs.LO↗

arXiv2021

Decentralized Observation of Discrete-Event Systems: At Least One Can Tell

We introduce a new decentralized observation condition which we call "at least one can tell" (OCT) and which attempts to capture the idea that for any possible behavior that a system can generate, at least one decentralized observation agent can tell whether that behavior was "good" or "bad", for given formal specifications of "good" and "bad". We provide several equivalent formulations of the OCT condition, and we relate it to (and show that it is different from) previously introduced joint observability. In fact, contrary to joint observability which is undecidable, we show that the OCT condition is decidable. We also show that when the condition holds, finite-state decentralized observers exist.

cs.FL↗

arXiv2020

Limited Lookahead Policies for the Control of Discrete-Event Systems: A Tutorial

Some problems in discrete-event systems (DES) model large, time-varying state spaces with complex legal languages. To address these problems, Chung et al. introduced limited lookahead policies (LLP) to provide online supervisory control for discrete-event systems. This seminal paper, along with an addendum of technical results, provided the field with a series of very important and powerful results, but in a notationally- and conceptually-dense manner. In this tutorial, we present Chung et al.'s problem formulation for online control and unravel the formal definitions and proofs from their original work with the aim of making the ideas behind limited lookahead accessible to all DES researchers. Finally, we introduce the Air Traffic Control problem as an example of an online control problem and demonstrate the synthesis of LLP supervisors.

eess.SY↗