A complexity hierarchy-based solution to the clausal subject puzzle in Turkish

This paper presents a novel analysis of subordinate clause structure in Turkish, focusing on subordinations formed by the following three suffixes: the infinitival -mA(K) with tenseless and (ir)realis usages, and -DIK/ -(y)ACAK with a (non)future temporal specification. We present a classification aligning each form on the Implicational Complementation Hierarchy (ICH) proposed in Wurmbrand and Lohninger (2020), which provides a solution for the subject puzzle observed with these clauses: only infinitival -mA(K) clauses with their (ir)realis use are compatible with being the subject of a transitive verb. We propose that (ir)realis infinitival clauses belong to the situation class in the ICH, and that this middle class is of the ideal semantic complexity and syntactic size for a clausal subject in Turkish.

Vacuity in synthesis

In reactive synthesis, one begins with a temporal specification $$\varphi $$ φ , and automatically synthesizes a system $$M$$ M such that $$M\models \varphi $$ M ⊧ φ . As many systems can satisfy a given specification, it is natural to seek ways to force the synthesis tool to synthesize systems that are of a higher quality, in some well-defined sense. In this article we focus on a well-known measure of the way in which a system satisfies its specification, namely vacuity. Our conjecture is that if the synthesized system M satisfies $$\varphi $$ φ non-vacuously, then M is likely to be closer to the user’s intent, because it satisfies $$\varphi $$ φ in a more “meaningful” way. Narrowing the gap between the formal specification and the designer’s intent in this way, automatically, is the topic of this article. Specifically, we propose a bounded synthesis method for achieving this goal. The notion of vacuity as defined in the context of model checking, however, is not necessarily refined enough for the purpose of synthesis. Hence, even when the synthesized system is technically non-vacuous, there are yet more interesting (equivalently, less vacuous) systems, and we would like to be able to synthesize them. To that end, we cope with the problem of synthesizing a system that is as non-vacuous as possible, given that the set of interesting behaviours with respect to a given specification induce a partial order on transition systems. On the theoretical side we show examples of specifications for which there is a single maximal element in the partial order (i.e., the most interesting system), a set of equivalent maximal elements, or a number of incomparable maximal elements. We also show examples of specifications that induce infinite chains of increasingly interesting systems. These results have implications on how non-vacuous the synthesized system can be. We implemented the new procedure in our synthesis tool PARTY. For this purpose we added to it the capability to synthesize a system based on a property which is a conjunction of universal and existential LTL formulas.

Effective Hybrid System Falsification Using Monte Carlo Tree Search Guided by QB-Robustness

Hybrid system falsification is an important quality assurance method for cyber-physical systems with the advantage of scalability and feasibility in practice than exhaustive verification. Falsification, given a desired temporal specification, tries to find an input of violation instead of a proof guarantee. The state-of-the-art falsification approaches often employ stochastic hill-climbing optimization that minimizes the degree of satisfaction of the temporal specification, given by its quantitative robust semantics. However, it has been shown that the performance of falsification could be severely affected by the so-called scale problem, related to the different scales of the signals used in the specification (e.g., rpm and speed): in the robustness computation, the contribution of a signal could be masked by another one. In this paper, we propose a novel approach to tackle this problem. We first introduce a new robustness definition, called QB-Robustness, which combines classical Boolean satisfaction and quantitative robustness. We prove that QB-Robustness can be used to judge the satisfaction of the specification and avoid the scale problem in its computation. QB-Robustness is exploited by a falsification approach based on Monte Carlo Tree Search over the structure of the formal specification. First, tree traversal identifies the sub-formulas for which it is needed to compute the quantitative robustness. Then, on the leaves, numerical hill-climbing optimization is performed, aiming to falsify such sub-formulas. Our in-depth evaluation on multiple benchmarks demonstrates that our approach achieves better falsification results than the state-of-the-art falsification approaches guided by the classical quantitative robustness, and it is largely not affected by the scale problem.

Temporal-based intrusion detection for IoV

The Internet of Vehicle (IoV) is an extension of Vehicle-to-Vehicle (V2V) communication that can improve vehicles’ fully autonomous driving capabilities. However, these communications are vulnerable to many attacks. Therefore, it is critical to provide run-time mechanisms to detect malware and stop the attackers before they manage to gain a foothold in the system. Anomaly-based detection techniques are convenient and capable of detecting off-nominal behavior by the component caused by zero-day attacks. One significant critical aspect when using anomaly-based techniques is ensuring the correct definition of the observed component’s normal behavior. In this paper, we propose using the task’s temporal specification as a baseline to define its normal behavior and identify temporal thresholds that give the system the ability to predict malicious tasks. By applying our solution on one use-case, we got temporal thresholds 20–40 % less than the one usually used to alarm the system about security violations. Using our boundaries ensures the early detection of off-nominal temporal behavior and provides the system with a sufficient amount of time to initiate recovery actions.