Extending Compositional Message Sequence Graphs

We extend the formal developments for message sequence charts (MSCs) to support scenarios with lost and found messages. We define a notion of extended compositional message sequence charts (ECMSCs) which subsumes the notion of compositional message sequence charts in expressive power but additionally allows to define lost and found messages explicitly. As usual, ECMSCs might be combined by means of choice and repetition towards (extended) compositional message sequence graphs. We show that - despite extended expressive power - model checking of monadic second-order logic (MSO) for this framework remains to be decidable. The key technique to achieve our results is to use an extended notion for linearizations

Realizability and Verification of MSC Graphs

Scenario-based specifications such as message sequence charts (MSC) offer an intuitive and visual way to describe design requirements. MSC-graphs allow convenient expression of multiple scenarios, and can be viewed as an early model of the system that can be subjected to a variety of analyses. Problems such as LTL model checking are undecidable for MSC-graphs in general, but are known to be decidable for the class of bounded MSC-graphs. Our first set of results concerns checking realizability of bounded MSC-graphs. An MSC-graph is realizable if there is a distributed implementation that generates precisely the behaviors in the graph. There are two notions of realizability, weak and safe, depending on whether or not we require the implementation to be deadlock-free. It is known that for a finite set of MSCs, weak realizability is coNP-complete while safe realizability has a polynomial-time solution. We establish that for bounded MSC-graphs, weak realizability is, surprisingly, undecidable, while safe realizability is in EXPSPACE. Our second set of results concerns verification of MSC-graphs. While checking properties of a graph G, besides verifying all the scenarios in the set L(G) of MSCs specified by G, it is desirable to verify all the scenarios in the set Lw(G)--the closure of G, that contains the implied scenarios that any distributed implementation of G must include. For checking whether a given MSC M is a possible behavior, checking M ∈ L(G) is NP-complete, but checking M ∈ Lw(G) has a quadratic solution. For temporal logic specifications, considering the closure makes the verification problem harder: while checking LTL properties of L(G) is PSPACE-complete for bounded graphs G, checking even simple local properties of Lw(G) is undecidable

A Kleene theorem and model checking algorithms for existentially bounded communicating automata

AbstractThe behavior of a network of communicating automata is called existentially bounded if communication events can be scheduled in such a way that the number of messages in transit is always bounded by a value that depends only on the machine, not the run itself. We show a Kleene theorem for existentially bounded communicating automata, namely the equivalence between communicating automata, globally cooperative compositional message sequence graphs, and monadic second order logic. Our characterization extends results for universally bounded models, where for each and every possible scheduling of communication events, the number of messages in transit is uniformly bounded. As a consequence, we give solutions in spirit of Madhusudan (2001) for various model checking problems on networks of communicating automata that satisfy our optimistic restriction

thurnauer: vt and vi, to paint in the second person

In these paintings, visual and verbal languages provide us with different maps of the same territory; and Thurnauer’s hybridized representations argue that the world can only be rendered through a dialogue, an interlocution of different forms, genres, media. We approach her work, not as viewers whose function is predicated through a gaze regulated according to the distorting demands of consumption or control, but as readers engaged in a critical activity seeing around the edges of historically produced versions of the self

Kansas environmental and resource study: A Great Plains model

There are no author-identified significant results in this report

Split Chords: Addressing the Federal Circuit Split in Music Sampling Copyright Infringement Cases

This Note offers a comprehensive analysis of the current circuit split regarding how the de minimis doctrine applies to music sampling in copyright infringement cases. Since the Sixth Circuit\u27s 2005 landmark decision in Bridgeport Music Inc. v. Dimension Films, critics, scholars and even judges have dissected the opinion and its bright line rule of “get a license or do not sample.” In May 2016, the Ninth Circuit issued its opinion in VMG Salsoul v. Ciccione. The Ninth Circuit explicitly declined to follow Bridgeport, holding that analyzing a music sampling copyright infringement case requires a substantial similarity analysis, including applying a de minimis analysis. The Ninth Circuit’s decision created a circuit split and an unsettled area of intellectual property law. This Note seeks to promote critical analysis of this contested area of law by exploring the underpinnings of the substantial similarity and de minimis doctrines, as well as the holdings of each case and their arguments. The Note offers three proposals regarding how courts should handle the circuit split, and in doing so creates a distinctive way of looking at the music sampling issue to help the federal judiciary frame the problem in a more expansive way