Browsing by Author "Nain, Sumit"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Linear vs. branching time: A semantical perspective
    (2009) Nain, Sumit; Vardi, Moshe Y.
    The discussion of the relative merits of linear versus branching-time goes back to early 1980s. The dominating belief has been that the linear-time framework is not expressive enough semantically, marking linear-time logics as weak. Here we examine this issue from the perspective of process equivalence, one of the most fundamental notions in concurrency theory. We postulate three principles that we view as fundamental to any discussion of process equivalence. First, we take contextual equivalence as the primary notion of equivalence. Second, we require the description of a process to fully specify all relevant behavioral aspects of the process. Finally, we require observable process behavior to be reflected in input/output behavior. Under these postulates the distinctions between the linear and branching semantics tend to evaporate. Applying them to the framework of transducers, we show that our postulates result in a unique notion of process equivalence, which is trace based, rather than tree based.
  • Thumbnail Image
    Item
    Solving Partial-Information Stochastic Parity Games
    (Association for Computing Machinery, 2013) Nain, Sumit; Vardi, Moshe Y.
    We study one-sided partial-information 2-player concurrent stochastic games with parity objectives. In such a game, one of the players has only partial visibility of the state of the game, while the other player has complete knowledge. In general, such games are known to be undecidable, even for the case of a single player (POMDP). These undecidability results depend crucially on player strategies that exploit an infinite amount of memory. However, in many applications of games, one is usually more interested in finding a finitememory strategy. We consider the problem of whether the player with partial information has a finite-memory winning strategy when the player with complete information is allowed to use an arbitrary amount of memory. We show that this problem is decidable.
  • Thumbnail Image
    Item
    Synthesis from Probabilistic Components
    (2013-10-29) Nain, Sumit; Vardi, Moshe Y.; Nakhleh, Luay K.; Baraniuk, Richard G.
    Synthesis is the automatic construction of a system from its specification. In classical synthesis algorithms, it is always assumed that the system is ``constructed from scratch'' rather than composed from reusable components. This, of course, rarely happens in real life, where almost every non-trivial commercial software system relies heavily on using libraries of reusable components. Furthermore, other contexts, such as web-service orchestration, can be modeled as synthesis of a system from a library of components. In contrast to classical synthesis, synthesis from components aims to build the desired system using components from a given library. In this dissertation, we consider the problem of control-flow synthesis from libraries of probabilistic components. We develop an automata-theoretic approach to solve the problem, investigate the expressive power of probabilistic control-flow, and examine the close relationship between synthesis from components and games with partial information.
  • Thumbnail Image
    Item
    Synthesis from Probabilistic Components
    (Institute of Theoretical Computer Science, Technical University of Braunschweig, 2014) Nain, Sumit; Lustig, Yoad; Vardi, Moshe Y.
    Synthesis is the automatic construction of a system from its specification. In classical synthesis algorithms, it is always assumed that the system is "constructed from scratch" rather than composed from reusable components. This, of course, rarely happens in real life, where almost every non-trivial commercial software system relies heavily on using libraries of reusable components. Furthermore, other contexts, such as web-service orchestration, can be modeled as synthesis of a system from a library of components. Recently, Lustig and Vardi introduced dataflow and control-flow synthesis from libraries of reusable components. They proved that dataflow synthesis is undecidable, while control-flow synthesis is decidable. In this work, we consider the problem of control-flow synthesis from libraries of probabilistic components . We show that this more general problem is also decidable.