8,973 research outputs found
On Redundancy Elimination Tolerant Scheduling Rules
In (Ferrucci, Pacini and Sessa, 1995) an extended form of resolution, called
Reduced SLD resolution (RSLD), is introduced. In essence, an RSLD derivation is
an SLD derivation such that redundancy elimination from resolvents is performed
after each rewriting step. It is intuitive that redundancy elimination may have
positive effects on derivation process. However, undesiderable effects are also
possible. In particular, as shown in this paper, program termination as well as
completeness of loop checking mechanisms via a given selection rule may be
lost. The study of such effects has led us to an analysis of selection rule
basic concepts, so that we have found convenient to move the attention from
rules of atom selection to rules of atom scheduling. A priority mechanism for
atom scheduling is built, where a priority is assigned to each atom in a
resolvent, and primary importance is given to the event of arrival of new atoms
from the body of the applied clause at rewriting time. This new computational
model proves able to address the study of redundancy elimination effects,
giving at the same time interesting insights into general properties of
selection rules. As a matter of fact, a class of scheduling rules, namely the
specialisation independent ones, is defined in the paper by using not trivial
semantic arguments. As a quite surprising result, specialisation independent
scheduling rules turn out to coincide with a class of rules which have an
immediate structural characterisation (named stack-queue rules). Then we prove
that such scheduling rules are tolerant to redundancy elimination, in the sense
that neither program termination nor completeness of equality loop check is
lost passing from SLD to RSLD.Comment: 53 pages, to appear on TPL
A Calculus of Bounded Capacities
Resource control has attracted increasing interest in foundational research on distributed systems. This paper focuses on space control and develops an analysis of space usage in the context of an ambient-like calculus with bounded capacities and weighed processes, where migration and activation require space. A type system complements the dynamics of the calculus by providing static guarantees that the intended capacity bounds are preserved throughout the computation
Late allocation and early release of physical registers
The register file is one of the critical components of current processors in terms of access time and power consumption. Among other things, the potential to exploit instruction-level parallelism is closely related to the size and number of ports of the register file. In conventional register renaming schemes, both register allocation and releasing are conservatively done, the former at the rename stage, before registers are loaded with values, and the latter at the commit stage of the instruction redefining the same register, once registers are not used any more. We introduce VP-LAER, a renaming scheme that allocates registers later and releases them earlier than conventional schemes. Specifically, physical registers are allocated at the end of the execution stage and released as soon as the processor realizes that there will be no further use of them. VP-LAER enhances register utilization, that is, the fraction of allocated registers having a value to be read in the future. Detailed cycle-level simulations show either a significant speedup for a given register file size or a reduction in the register file size for a given performance level, especially for floating-point codes, where the register file pressure is usually high.Peer ReviewedPostprint (published version
Dynamic Dependency Collapsing
In this dissertation, we explore the concept of dynamic dependency collapsing. Performance increases in computer architecture are always introduced by exploiting additional parallelism when the clock speed is fixed. We show that further improvements are possible even when the available parallelism in programs are exhausted. This performance improvement is possible due to executing instructions in parallel that would ordinarily have been serialized. We call this concept dependency collapsing. We explore existing techniques that exploit parallelism and show which of them fall under the umbrella of dependency collapsing. We then introduce two dependency collapsing techniques of our own. The first technique collapses data dependencies by executing two normally dependent instructions together by fusing them. We show that exploiting the additional parallelism generated by collapsing these dependencies results in a performance increase. Our second technique collapses resource dependencies to execute instructions that would normally have been serialized due to resource constraints in the processor. We show that it is possible to take advantage of larger in-processor structures while avoiding the power and area penalty this often implies
A generic framework for the analysis and specialization of logic programs
The relationship between abstract interpretation and partial
deduction has received considerable attention and (partial) integrations have been proposed starting from both the partial deduction and abstract interpretation perspectives. In this work we present what we argĂŒe is the first fully described generic algorithm for efñcient and precise integration of abstract interpretation and partial deduction. Taking as starting point state-of-the-art algorithms for context-sensitive, polyvariant abstract interpretation and (abstract) partial deduction, we present
an algorithm which combines the best of both worlds. Key ingredients include the accurate success propagation inherent to abstract interpretation and the powerful program transformations achievable by partial deduction. In our algorithm, the calis which appear in the analysis graph
are not analyzed w.r.t. the original definition of the procedure but w.r.t. specialized definitions of these procedures. Such specialized definitions are obtained by applying both unfolding and abstract executability. Our framework is parametric w.r.t. different control strategies and abstract domains. Different combinations of such parameters correspond to existing algorithms for program analysis and specialization. Simultaneously, our approach opens the door to the efñcient computation of strictly more
precise results than those achievable by each of the individual techniques.
The algorithm is now one of the key components of the CiaoPP analysis
and specialization system
Crafting symbolic geographies in modern Turkey
Place is a social site of meaning and memory. The critical appreciation of place and its link to power in toponymic studies involve the identity politics of place naming. This paper discusses the relationship between the naming of places and identity construction in Turkey. First, conceptualized as a hegemonic practice, the Turkification of toponyms in the Kurdish region of the country is argued to be part of a broader system of assimilation. Supported by the imposition of particular ethno- nationalist narratives on the past, and conducted with concomitant processes of linguistic and demographic design, top-down and centralized engineering of the countryâs toponymic order has two sides; the construction of symbolic Turkish spaces and the cultural erosion of Kurdishness. Later, the research examines the act of naming places as a Kurdish strategy of resistance and a cultural right. As an attempt to remove spatial and linguistic injustice, Kurdish toponymic practices aim at re-asserting the âselfâ and reclaiming memory, space and identity through the re-introduction of former place names or new alternatives that are conducive to the reparation of the Kurdish identity. The discursive and material struggle over space and the clash between the Turkish and Kurdish discourses on naming places reflect the overall structure of social and political power relations in Turkey
Enumerating Independent Linear Inferences
A linear inference is a valid inequality of Boolean algebra in which each
variable occurs at most once on each side. Equivalently, it is a linear rewrite
rule on Boolean terms that constitutes a valid implication. Linear inferences
have played a significant role in structural proof theory, in particular in
models of substructural logics and in normalisation arguments for deep
inference proof systems.
In this work we leverage recently developed graphical representations of
linear formulae to build an implementation that is capable of more efficiently
searching for switch-medial-independent inferences. We use it to find four
`minimal' 8-variable independent inferences and also prove that no smaller ones
exist; in contrast, a previous approach based directly on formulae reached
computational limits already at 7 variables. Two of these new inferences derive
some previously found independent linear inferences. The other two (which are
dual) exhibit structure seemingly beyond the scope of previous approaches we
are aware of; in particular, their existence contradicts a conjecture of Das
and Strassburger.
We were also able to identify 10 minimal 9-variable linear inferences
independent of all the aforementioned inferences, comprising 5 dual pairs, and
present applications of our implementation to recent `graph logics'.Comment: 33 pages, 3 figure
- âŠ