Towards an Effective Decision Procedure for LTL formulas with Constraints

This paper presents an ongoing work that is part of a more wide-ranging project whose final scope is to define a method to validate LTL formulas w.r.t. a program written in the timed concurrent constraint language tccp, which is a logic concurrent constraint language based on the concurrent constraint paradigm of Saraswat. Some inherent notions to tccp processes are non-determinism, dealing with partial information in states and the monotonic evolution of the information. In order to check an LTL property for a process, our approach is based on the abstract diagnosis technique. The concluding step of this technique needs to check the validity of an LTL formula (with constraints) in an effective way. In this paper, we present a decision method for the validity of temporal logic formulas (with constraints) built by our abstract diagnosis technique.Comment: Part of WLPE 2013 proceedings (arXiv:1308.2055

Assyrian imperial frontiers during the first millennium BC. The case of the Iraqi Middle Euphrates

Many recent studies have dealt with the nature of the Assyrian imperial frontiers, demonstrating how diversified they have been through time and space, with cases such as Khabur and Upper Tigris regions. On the other hand, the Assyrian periphery along the Iraqi middle Euphrates – ancient region of Suḫu – is archaeologically less known. The archaeological investigations before the construction of the Haditha Dam revealed many sites datable to the Iron Age, some of which seemed to have a marked military nature. The region was therefore seen as a seat for fortresses of the Assyrian Empire. The present paper, through a preliminary analysis of the material culture of the sites, the settlement pattern using GIS and satellite images, aims to suggest a more multi-faced nature of the settlement in the region

An Abstract Interpretation Framework for Diagnosis and Verification of Timed Concurrent Constraint Languages

In this thesis, we propose a semantic framework for tccp based on abstract interpretation with the main purpose of formally verifying and debugging tccp programs. A key point for the efficacy of the resulting methodologies is the adequacy of the concrete semantics. Thus, in this thesis, much effort has been devoted to the development of a suitable small-step denotational semantics for the tccp language to start with. Our denotational semantics models precisely the small-step behavior of tccp and is suitable to be used within the abstract interpretation framework. Namely, it is defined in a compositional and bottom-up way, it is as condensed as possible (it does not contain redundant elements), and it is goal-independent (its calculus does not depend on the semantic evaluation of a specific initial agent). Another contribution of this thesis is the definition (by abstraction of our small-step denotational semantics) of a big-step denotational semantics that abstracts away from the information about the evolution of the state and keeps only the the first and the last (if it exists) state. We show that this big-step semantics is essentially equivalent to the input-output semantics. In order to fulfill our goal of formally validate tccp programs, we build different approximations of our small-step denotational semantics by using standard abstract interpretation techniques. In this way we obtain debugging and verification tools which are correct by construction. More specifically, we propose two abstract semantics that are used to formally debug tccp programs. The first one approximates the information content of tccp behavioral traces, while the second one approximates our small-step semantics with temporal logic formulas. By applying abstract diagnosis with these abstract semantics we obtain two fully-automatic verification methods for tccp

USING AN ACTIVE OPTICAL SENSOR TO IMPROVE NITROGEN MANAGEMENT IN CORN PRODUCTION

Corn nitrogen (N) applications are still done on a field basis in Kentucky, according to previous crop, soil tillage management and soil drainage. Soil tests, as well as plant analysis for N, are not very useful in making N fertilizer rate recommendations for corn. Recommended rates assume that only 1/3 to 2/3 of applied N is recovered, variability largely due to the strong affect of weather on the release of soil N and fertilizer N fate. Many attempts have been made to apply N in a more precise and efficient way. Two experiments were conducted at Spindeltop, the University of Kentucky’s experimental farm near Lexington, over two years (2010, 2011), using a commercially available active optical sensor (GreanSeekerTM) to compute the normalized difference vegetative index (NDVI), and with this tool/index assess the possibility of early (V4-V6) N deficiency detection, grain yield prediction by NDVI with and without side-dressed N, and determination of the confounding effect of soil background on NDVI measurements. Results indicated that the imposed treatments affected grain yield, leaf N, grain N and grain N removal. Early N deficiency detection was possible with NDVI. The NDVI value tended to saturate in grain yield prediction models. The NDVI was affected by tillage management (residue/soil color background differences), which should be taken into account when using NDVI to predict grain yield. Side-dress N affected NDVI readings taken one week after side-dressing, reducing soil N variability and plant N nutrition. There is room for improvement in the use of this tool in corn N management

The United Postal \u3cem\u3eService\u3c/em\u3e—The One Word that Makes all the Difference

In recent months, the United States Postal Service (USPS) has taken center stage on a number of intersecting issues in our society: the pandemic; the upcoming election (through mail-in voting) and the controversy surrounding the appointment of Louis DeJoy to the position of Postmaster General. President Donald Trump has frequently made derogatory remarks regarding the Postal Service, calling it a “joke,” and has made repeated statements encouraging its privatization. However, President Trump’s rhetoric (as well as the rhetoric of others before him) obfuscates the critical mission of the USPS – to provide service to every American in the country; not simply through its Universal Service Obligation but through other particularly public functions that are largely unique to this agency. This essay unmasks this rhetoric and argues that privatization is not a good fit for USPS. Through an examination of both the debates of privatization and the implications of becoming a profit-making business, we show how these goals are misaligned with the central mission of the Postal Service. Americans rely on USPS for a number of essential functions that it would be impossible to carry out on a for-profit basis. Now, more than ever, we need to focus on the key public mission of USPS to serve all Americans

Abstract Diagnosis for Timed Concurrent Constraint programs

The Timed Concurrent Constraint Language (tccp in short) is a concurrent logic language based on the simple but powerful concurrent constraint paradigm of Saraswat. In this paradigm, the notion of store-as-value is replaced by the notion of store-as-constraint, which introduces some differences w.r.t. other approaches to concurrency. In this paper, we provide a general framework for the debugging of tccp programs. To this end, we first present a new compact, bottom-up semantics for the language that is well suited for debugging and verification purposes in the context of reactive systems. We also provide an abstract semantics that allows us to effectively implement debugging algorithms based on abstract interpretation. Given a tccp program and a behavior specification, our debugging approach automatically detects whether the program satisfies the specification. This differs from other semiautomatic approaches to debugging and avoids the need to provide symptoms in advance. We show the efficacy of our approach by introducing two illustrative examples. We choose a specific abstract domain and show how we can detect that a program is erroneous.Comment: 16 page

Provably Correct Floating-Point Implementation of a Point-In-Polygon Algorithm

The problem of determining whether or not a point lies inside a given polygon occurs in many applications. In air traffic management concepts, a correct solution to the point-in-polygon problem is critical to geofencing systems for Unmanned Aerial Vehicles and in weather avoidance applications. Many mathematical methods can be used to solve the point-in-polygon problem. Unfortunately, a straightforward floating- point implementation of these methods can lead to incorrect results due to round-off errors. In particular, these errors may cause the control flow of the program to diverge with respect to the ideal real-number algorithm. This divergence potentially results in an incorrect point-in- polygon determination even when the point is far from the edges of the polygon. This paper presents a provably correct implementation of a point-in-polygon method that is based on the computation of the winding number. This implementation is mechanically generated from a source- to-source transformation of the ideal real-number specification of the algorithm. The correctness of this implementation is formally verified within the Frama-C analyzer, where the proof obligations are discharged using the Prototype Verification System (PVS)