Mohammad Raza

Automatic Parallelization with Separation Logic

Separation logic is a recent approach to the analysis of pointer programs in which resource separation is expressed with a logical connective in assertions that describe the state at any given point in the program. We extend this approach to express properties of memory separation between different points in the program, and present an algorithm for determining independences between program statements which can be used for parallelization.

Footprints in Local Reasoning

Local reasoning about programs exploits the natural local behaviour common in programs by focussing on the footprint - that part of the resource accessed by the program. We address the problem of formally characterising and analysing the footprint notion for abstract local functions introduced by Calcagno, O Hearn and Yang. With our definition, we prove that the footprints are the only essential elements required for a complete specification of a local function. We formalise the notion of small specifications in local reasoning and show that for well-founded resource models, a smallest specification always exists that only includes the footprints, and also present results for the non-well-founded case. Finally, we use this theory of footprints to investigate the conditions under which the footprints correspond to the smallest safe states. We present a new model of RAM in which, unlike the standard model, the footprints of every program correspond to the smallest safe states, and we also identify a general condition on the primitive commands of a programming language which guarantees this property for arbitrary models.

Mixed-Initiative Approaches to Global Editing in Slideware

Good alignment and repetition of objects across presentation slides can facilitate visual processing and contribute to audience understanding. However, creating and maintaining such consistency during slide design is difficult. To solve this problem, we present two complementary tools: (1) StyleSnap, which increases the alignment and repetition of objects by adaptively clustering object edge positions and allowing parallel editing of all objects snapped to the same spatial extent; and (2) FlashFormat, which infers the least-general generalization of editing examples and applies it throughout the selected range. In user studies of repetitive styling task performance, StyleSnap and FlashFormat were 4-5 times and 2-3 times faster respectively than conventional editing. Both use a mixed-initiative approach to improve the consistency of slide decks and generalize to any situations involving direct editing across disjoint visual spaces.