28 research outputs found
Natively probabilistic computation
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2009.Includes bibliographical references (leaves 129-135).I introduce a new set of natively probabilistic computing abstractions, including probabilistic generalizations of Boolean circuits, backtracking search and pure Lisp. I show how these tools let one compactly specify probabilistic generative models, generalize and parallelize widely used sampling algorithms like rejection sampling and Markov chain Monte Carlo, and solve difficult Bayesian inference problems. I first introduce Church, a probabilistic programming language for describing probabilistic generative processes that induce distributions, which generalizes Lisp, a language for describing deterministic procedures that induce functions. I highlight the ways randomness meshes with the reflectiveness of Lisp to support the representation of structured, uncertain knowledge, including nonparametric Bayesian models from the current literature, programs for decision making under uncertainty, and programs that learn very simple programs from data. I then introduce systematic stochastic search, a recursive algorithm for exact and approximate sampling that generalizes a popular form of backtracking search to the broader setting of stochastic simulation and recovers widely used particle filters as a special case. I use it to solve probabilistic reasoning problems from statistical physics, causal reasoning and stereo vision. Finally, I introduce stochastic digital circuits that model the probability algebra just as traditional Boolean circuits model the Boolean algebra.(cont.) I show how these circuits can be used to build massively parallel, fault-tolerant machines for sampling and allow one to efficiently run Markov chain Monte Carlo methods on models with hundreds of thousands of variables in real time. I emphasize the ways in which these ideas fit together into a coherent software and hardware stack for natively probabilistic computing, organized around distributions and samplers rather than deterministic functions. I argue that by building uncertainty and randomness into the foundations of our programming languages and computing machines, we may arrive at ones that are more powerful, flexible and efficient than deterministic designs, and are in better alignment with the needs of computational science, statistics and artificial intelligence.by Vikash Kumar Mansinghka.Ph.D
Configuration Analysis for Large Scale Feature Models: Towards Speculative-Based Solutions
Los sistemas de alta variabilidad son sistemas de software en los que la gestión de la
variabilidad es una actividad central. Algunos ejemplos actuales de sistemas de alta
variabilidad son el sistema web de gesión de contenidos Drupal, el núcleo de Linux,
y las distribuciones Debian de Linux.
La configuración en sistemas de alta variabilidad es la selección de opciones
de configuración según sus restricciones de configuración y los requerimientos de
usuario. Los modelos de características son un estándar “de facto” para modelar las
funcionalidades comunes y variables de sistemas de alta variabilidad. No obstante,
el elevado número de componentes y configuraciones que un modelo de características
puede contener hacen que el análisis manual de estos modelos sea una tarea muy
costosa y propensa a errores. Así nace el análisis automatizado de modelos de características
con mecanismos y herramientas asistidas por computadora para extraer
información de estos modelos. Las soluciones tradicionales de análisis automatizado
de modelos de características siguen un enfoque de computación secuencial para
utilizar una unidad central de procesamiento y memoria. Estas soluciones son adecuadas
para trabajar con sistemas de baja escala. Sin embargo, dichas soluciones demandan
altos costos de computación para trabajar con sistemas de gran escala y alta
variabilidad. Aunque existan recusos informáticos para mejorar el rendimiento de
soluciones de computación, todas las soluciones con un enfoque de computación secuencial
necesitan ser adaptadas para el uso eficiente de estos recursos y optimizar su
rendimiento computacional. Ejemplos de estos recursos son la tecnología de múltiples
núcleos para computación paralela y la tecnología de red para computación distribuida.
Esta tesis explora la adaptación y escalabilidad de soluciones para el analisis automatizado
de modelos de características de gran escala. En primer lugar, nosotros
presentamos el uso de programación especulativa para la paralelización de soluciones.
Además, nosotros apreciamos un problema de configuración desde otra perspectiva,
para su solución mediante la adaptación y aplicación de una solución no
tradicional. Más tarde, nosotros validamos la escalabilidad y mejoras de rendimiento
computacional de estas soluciones para el análisis automatizado de modelos de características
de gran escala.
Concretamente, las principales contribuciones de esta tesis son:
• Programación especulativa para la detección de un conflicto mínimo y
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preferente. Los algoritmos de detección de conflictos mínimos determinan
el conjunto mínimo de restricciones en conflicto que son responsables de comportamiento
defectuoso en el modelo en análisis. Nosotros proponemos una
solución para, mediante programación especulativa, ejecutar en paralelo y reducir
el tiempo de ejecución de operaciones de alto costo computacional que
determinan el flujo de acción en la detección de conflicto mínimo y preferente
en modelos de características de gran escala.
• Programación especulativa para un diagnóstico mínimo y preferente. Los
algoritmos de diagnóstico mínimo determinan un conjunto mínimo de restricciones
que, por una adecuada adaptación de su estado, permiten conseguir un
modelo consistente o libre de conflictos. Este trabajo presenta una solución
para el diagnóstico mínimo y preferente en modelos de características de gran
escala mediante la ejecución especulativa y paralela de operaciones de alto
costo computacional que determinan el flujo de acción, y entonces disminuir
el tiempo de ejecución de la solución.
• Completar de forma mínima y preferente una configuración de modelo
por diagnóstico. Las soluciones para completar una configuración parcial
determinan un conjunto no necesariamente mínimo ni preferente de opciones
para obtener una completa configuración. Esta tesis soluciona el completar
de forma mínima y preferente una configuración de modelo mediante técnicas
previamente usadas en contexto de diagnóstico de modelos de características.
Esta tesis evalua que todas nuestras soluciones preservan los valores de salida esperados,
y también presentan mejoras de rendimiento en el análisis automatizado de
modelos de características con modelos de gran escala en las operaciones descrita
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Working notes of the 1991 spring symposium on constraint-based reasoning
Proceedings of the 21st Conference on Formal Methods in Computer-Aided Design – FMCAD 2021
The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing
Multi-level simulation of nano-electronic digital circuits on GPUs
Simulation of circuits and faults is an essential part in design and test validation tasks of contemporary nano-electronic digital integrated CMOS circuits.
Shrinking technology processes with smaller feature sizes and strict performance and reliability requirements demand not only detailed validation of the functional properties of a design, but also accurate validation of non-functional aspects including the timing behavior. However, due to the rising complexity of the circuit behavior and the steady growth of the designs with respect to the transistor count, timing-accurate simulation of current designs requires a lot of computational effort which can only be handled by proper abstraction and a high degree of parallelization.
This work presents a simulation model for scalable and accurate timing simulation of digital circuits on data-parallel graphics processing unit (GPU) accelerators.
By providing compact modeling and data-structures as well as through exploiting multiple dimensions of parallelism, the simulation model enables not only fast and timing-accurate simulation at logic level, but also massively-parallel simulation with switch level accuracy.
The model facilitates extensions for fast and efficient fault simulation of small delay faults at logic level, as well as first-order parametric and parasitic faults at switch level.
With the parallelization on GPUs, detailed and scalable simulation is enabled that is applicable even to multi-million gate designs.
This way, comprehensive analyses of realistic timing-related faults in presence of process- and parameter variations are enabled for the first time.
Additional simulation efficiency is achieved by merging the presented methods in a unified simulation model, that allows to combine the unique advantages of the different levels of abstraction in a mixed-abstraction multi-level simulation flow to reach even higher speedups.
Experimental results show that the implemented parallel approach achieves unprecedented simulation throughput as well as high speedup compared to conventional timing simulators.
The underlying model scales for multi-million gate designs and gives detailed insights into the timing behavior of digital CMOS circuits, thereby enabling large-scale applications to aid even highly complex design and test validation tasks
Third Conference on Artificial Intelligence for Space Applications, part 1
The application of artificial intelligence to spacecraft and aerospace systems is discussed. Expert systems, robotics, space station automation, fault diagnostics, parallel processing, knowledge representation, scheduling, man-machine interfaces and neural nets are among the topics discussed
Proceedings of the 22nd Conference on Formal Methods in Computer-Aided Design – FMCAD 2022
The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing
Proceedings of the 22nd Conference on Formal Methods in Computer-Aided Design – FMCAD 2022
The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing