5,754 research outputs found
Automating Fine Concurrency Control in Object-Oriented Databases
Several propositions were done to provide adapted concurrency control to
object-oriented databases. However, most of these proposals miss the fact that
considering solely read and write access modes on instances may lead to less
parallelism than in relational databases! This paper cope with that issue, and
advantages are numerous: (1) commutativity of methods is determined a priori
and automatically by the compiler, without measurable overhead, (2) run-time
checking of commutativity is as efficient as for compatibility, (3) inverse
operations need not be specified for recovery, (4) this scheme does not
preclude more sophisticated approaches, and, last but not least, (5) relational
and object-oriented concurrency control schemes with read and write access
modes are subsumed under this proposition
Compensation methods to support generic graph editing: A case study in automated verification of schema requirements for an advanced transaction model
Compensation plays an important role in advanced transaction models, cooperative work, and workflow systems. However, compensation operations are often simply written as a^−1 in
transaction model literature. This notation ignores any operation parameters, results, and side effects. A schema designer intending to use an advanced transaction model is expected (required) to write correct method code. However, in the days of cut-and-paste, this is much easier said than done. In this paper, we demonstrate the feasibility of using an off-the-shelf theorem prover (also called a proof assistant) to perform automated verification of compensation requirements for an OODB schema. We report on the results of a case study in verification for a particular advanced transaction model that supports cooperative applications. The case study is based on an OODB schema that provides generic graph editing functionality for the creation, insertion, and manipulation of nodes and links
On a boundary-localized Higgs boson in 5D theories
In the context of a simple five-dimensional (5D) model with bulk matter
coupled to a brane-localized Higgs boson, we point out a new non-commutativity
in the 4D calculation of the mass spectrum for excited fermion towers: the
obtained expression depends on the choice in ordering the limits, N->infinity
(infinite Kaluza-Klein tower) and epsilon->0 (epsilon being the parameter
introduced for regularizing the Higgs Dirac peak). This introduces the physical
question of which one is the correct order; we then show that the two possible
orders of regularization (called I and II) are physically equivalent, as both
can typically reproduce the measured observables, but that the one with less
degrees of freedom (I) could be uniquely excluded by future experimental
constraints. This conclusion is based on the exact matching between the 4D and
5D analytical calculations of the mass spectrum - via the regularizations of
type I and II. Beyond a deeper insight into the Higgs peak regularizations,
this matching also allows us to confirm the validity of the usual 5D
mixed-formalism and to clarify the UV cut-off procedure. All the conclusions,
deduced from regularizing the Higgs peak through a brane shift or a smoothed
square profile, are expected to remain similar in realistic models with a
warped extra-dimension.Comment: 29 pages, 2 table
On Multi-step BCFW Recursion Relations
In this paper, we extensively investigate the new algorithm known as the
multi-step BCFW recursion relations. Many interesting mathematical properties
are found and understanding these aspects, one can find a systematic way to
complete the calculation of amplitude after finite, definite steps and get the
correct answer, without recourse to any specific knowledge from field theories,
besides mass dimension and helicities. This process consists of the pole
concentration and inconsistency elimination. Terms that survive inconsistency
elimination cannot be determined by the new algorithm. They include polynomials
and their generalizations, which turn out to be useful objects to be explored.
Afterwards, we apply it to the Standard Model plus gravity to illustrate its
power and limitation. Ensuring its workability, we also tentatively discuss how
to improve its efficiency by reducing the steps.Comment: 38 pages, 13 figures, 3 appendice
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