Systems Modeling for novice engineers to comprehend software products better

One of the key challenges for a novice engineer in a product company is to comprehend the product sufficiently and quickly. It can take anywhere from six months to several years for them to attain mastery but they need to start delivering results much before. SaaS (Software-as-a-Service) products have sophisticated system architecture which adds to the time and effort of understanding them. On the other hand, time available to new hires for product understanding continues to be short and getting shorter, given the pressure to deliver more in less time. Constructivist theory views learning as a personal process in which the learner constructs new knowledge for themselves. Building and refining a mental model is the key way in which they learn, similar to how the brain operates. This paper presents an approach to improve system comprehension process by using a system model that a) acts as a transitional object to aid and refine the mental model of the learner, and b) captures the current understanding of the dynamics of the software system in a way that can be reasoned with and simulated. We have adapted discrete systems modeling techniques and used a transition system as a lightweight modeling language. Such a model can be used by novice engineers during their product ramp-up phase to build a model of the software system that captures their knowledge of the system and aid their mental model. The paper also presents a learning approach in which the learners create and refine these models iteratively using the available and newly uncovered knowledge about the software system. We hypothesize that by leveraging this modeling language and approach, novice engineers can reduce the time it takes them to achieve desired proficiency level of system comprehension. This paper presents early ideas on this language and approach.Comment: 5 page

Polymorphic Type Reconstruction Using Type Equations

The W algorithm of Milner [Mil78] and its numerous variants [McA98,LY98,YTMW00] implement type reconstruction by building type substitutions. We define an algorithm W centered around building type equations rather than substitutions. The design of W is motivated by the belief that reasoning with substitutions is awkward

Employing Timed CTL assumptions in modular veri cation of invariant properties of real time component based systems Employing Timed CTL assumptions in modular verification of invariant properties of real time component based systems

Abstract The extant assume-guarantee approaches for real time systems use timed language or equivalently timed automata based specifications of assumptions. But discharging timed automata assumptions on environment models requires simulation-checking. On the other hand, discharging an assumption in Timed Computational Tree Logic (TCTL) can be done by processing the assumption as a model-checking query on the environment timed automaton. The region-explosion problem is encountered in both simulation-checking and TCTL modelchecking. But, while efficient tool support is there for countering region-explosion in TCTL model checking, there is no efficient tool support for the same in case of simulation-checking. Therefore, in this paper we present a method for employing TCTL assumptions in modular assume-guarantee verification of invariant properties of real-time component based systems. So as to accommodate TCTL assume-guarantees, we instantiate boolean input and output variables for timed automata representing a continuous pure signal interface. We also address complexity issues arising by instantiating boolean input-output variables. This paper only deals with invariant guarantees (like safety guarantees), with the hope of extending it to liveness guarantees in case of bounded response systems

On Lower Bounds for the Matrix Chain Ordering Problem

This paper shows that the radix model is not reasonable for solving the Matrix Chain Ordering Problem. In particular, to have an n-matrix instance of this problem with an optimal parenthesization of depth \Theta(n) in the worst case requires the matrix dimensions to be exponential in n. Considering bit complexity, a worst case lower bound of \Omega\Gamma n 2 ) is given. This worst case lower bound is parameterized and, depending on the optimal product tree depth, it goes from \Omega\Gamma n 2 ) down to \Omega\Gamma n lg n). Also, this paper gives an \Omega\Gamma n lg n) work lower bound for the Matrix Chain Ordering Problem for a class of algorithms on the atomic comparison model with unit cost comparisons. This lower bound, to the authors' knowledge, captures all known algorithms for solving the Matrix Chain Ordering Problem, but does not consider bit operations. Finally, a trade-off is given between the bit complexity lower bound and the atomic comparison based lower bound. This..

Requirements for and evaluation of RMI protocols for scientific computing

Distributed software component architectures provide a promising approach to the problem of building large scale, scientific Grid applications [18]. Communicatio in these co mpo nent architectures is based on Remote Method Invocation ( MI) pro: co ls thatallo wo neso: ware co mp o ent to invo e the functio alityo f ano ther. Examples include Java remo# method invocatio (Java MI)[25] and the new Simple Object Access Protocol (SOAP) [15]. SOAP has the advantage that many proK#T#0R g languages andco mpo nent frameworks can support it. This paper describes experiments sho wing that SOAP by itself is no e#cient eno ugh fo large scale scientific applicatio s. Ho wever, when it is embedded in a multi-pro# co MI framewoK , SOAP can be effectively used as a universal control protocol, that can be swapped out by faster, more special purpose protocols when large data transfer speeds are needed

Synthesis of High-Performance Parallel Programs for a Class of Ab Initio Quantum Chemistry Models

Invited Paper This paper provides an overview of a program synthesis system for a class of quantum chemistry computations. These computations are expressible as a set of tensor contractions and arise in electronic structure modeling. The input to the system is a a high-level specification of the computation, from which the system can synthesize high-performance parallel code tailored to the characteristics of th