140,716 research outputs found
Comments on Background Independence and Gauge Redundancies
We describe the definition and the role background independence and the
closely related notion of diffeomorphism invariance play in modern string
theory. These important concepts are transformed by a new understanding of
gauge redundancies and their implementation in non-perturbative quantum field
theory and quantum gravity. This new understanding also suggests a new role for
the so-called background-independent approaches to directly quantize the
gravitational field. This article is intended for a general audience, and is
based on a plenary talk given in the Loops 2007 conference in Morelia, Mexico.Comment: 8 pages, 1 figure, to appear in Adv. Sci. Let
String processing model for knowledge-driven systems
The purpose of the work is to confirm experimentally theoretical estimates for time complexity of operations of the string processing model linked with the metric space for solving data processing problems in knowledge-driven systems including the research and comparison of the operation characteristics of these operations with the characteristics of similar operations for the most relevant data structures. Integral and unit testing were used to obtain the results of the performed computational experiments and verify their correctness. The C \ C++ implementation of operations of the string processing model was tested. The paper gives definitions of concepts necessary for the calculation of metric features calculated over strings. As a result of the experiments, theoretical estimates of the computational complexity of the implemented operations and the validity of the choice of parameters of the used data structures were confirmed, which ensures near-optimal throughput and operation time indicators of operations. According to the obtained results, the advantage is the ability to guarantee the time complexity of the string processing operations no higher than O at all stages of a life cycle of data structures used to represent strings, from their creation to destruction, which allows for high throughput in data processing and responsiveness of systems built on the basis of the implemented operations. In case of solving particular string processing problems and using more suitable for these cases data structures such as vector or map the implemented operations have disadvantages meaning they are inferior in terms of the amount of data processed per time unit. The string processing model is focused on the application in knowledge-driven systems at the data management level.The purpose of the work is to confirm experimentally theoretical estimates for time complexity of operations of the string processing model linked with the metric space for solving data processing problems in knowledge-driven systems including the research and comparison of the operation characteristics of these operations with the characteristics of similar operations for the most relevant data structures. Integral and unit testing were used to obtain the results of the performed computational experiments and verify their correctness. The C \ C++ implementation of operations of the string processing model was tested. The paper gives definitions of concepts necessary for the calculation of metric features calculated over strings. As a result of the experiments, theoretical estimates of the computational complexity of the implemented operations and the validity of the choice of parameters of the used data structures were confirmed, which ensures near-optimal throughput and operation time indicators of operations. According to the obtained results, the advantage is the ability to guarantee the time complexity of the string processing operations no higher than O at all stages of a life cycle of data structures used to represent strings, from their creation to destruction, which allows for high throughput in data processing and responsiveness of systems built on the basis of the implemented operations. In case of solving particular string processing problems and using more suitable for these cases data structures such as vector or map the implemented operations have disadvantages meaning they are inferior in terms of the amount of data processed per time unit. The string processing model is focused on the application in knowledge-driven systems at the data management level
A Concurrency-Agnostic Protocol for Multi-Paradigm Concurrent Debugging Tools
Today's complex software systems combine high-level concurrency models. Each
model is used to solve a specific set of problems. Unfortunately, debuggers
support only the low-level notions of threads and shared memory, forcing
developers to reason about these notions instead of the high-level concurrency
models they chose.
This paper proposes a concurrency-agnostic debugger protocol that decouples
the debugger from the concurrency models employed by the target application. As
a result, the underlying language runtime can define custom breakpoints,
stepping operations, and execution events for each concurrency model it
supports, and a debugger can expose them without having to be specifically
adapted.
We evaluated the generality of the protocol by applying it to SOMns, a
Newspeak implementation, which supports a diversity of concurrency models
including communicating sequential processes, communicating event loops,
threads and locks, fork/join parallelism, and software transactional memory. We
implemented 21 breakpoints and 20 stepping operations for these concurrency
models. For none of these, the debugger needed to be changed. Furthermore, we
visualize all concurrent interactions independently of a specific concurrency
model. To show that tooling for a specific concurrency model is possible, we
visualize actor turns and message sends separately.Comment: International Symposium on Dynamic Language
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