5916479
Enumeration of 2 -connected Loopless 4 -regular Maps on the Plane
In this paper rooted (near-) 4-regular maps on the plane are counted with respect to the root-valency, the number of edges, the number of inner faces, the number of non-root vertex loops, the number of non-root vertex blocks, and the number of multi-edges. As special cases, formulae of several types of rooted 4-regular maps such as 2-connected 4-regular planar maps, rooted 2-connected (connected) 4-regular planar maps without loops are also presented. Several known results on 4-regular maps and trees of Tutte are also concluded. Finally, asymptotic formulae for the numbers of those types of maps are given.
26526878
Chromatic sums of 2-edge-connected maps on the plane
This paper provides the chromatic sum function equation of rooted 2-edge-connected maps on the plane. The enumerating function equations of rooted biloopless maps, rooted nonseparable maps, rooted 2-edge-connected bipartite maps and rooted loopless Eulerian maps on the plane are derived by the chromatic sum function equation of rooted 2-edge-connected maps on the plane. Moreover, some explicit expressions of enumerating functions are also derived.
3705093
MINMAX optimal video summarization
The need for video summarization originates primarily from a viewing time constraint. A shorter version of the original video sequence is desirable in a number of applications. Clearly, a shorter version is also necessary in applications where storage, communication bandwidth and/or power are limited. In this paper, our work is based on a MINMAX optimization formulation with viewing time, frame skip and bit rate constraints. New metrics for missing frame and video summary distortions are introduced. Optimal algorithm based on dynamic programming is presented along with experimental results.
5857019
A Compiler Framework for Tiling Imperfectly-Nested Loops
This paper presents an integrated compiler framework for tiling a class of nontrivial imperfectly-nested loops such that cache locality is improved. We develop a new memory cost model to analyze data reuse in terms of both the cache and the TLB, based on which we compute the tile size with or without array duplication. We determine whether to duplicate arrays for tiling by comparing the respective exploited reuse factors. The preliminary results with several benchmark programs show that the transformed programs achieve a speedup of 1.09 to 3.82 over the original programs.
10771836
Detection and repair of software errors in hierarchical sensor networks
Sensor networks are being increasingly deployed for collecting critical data in various applications. Once deployed, a sensor network may experience faults at the individual node level or at an aggregate network level due to design errors in the protocol, implementation errors, or deployment conditions that are significantly different from the target environment. In many applications, the deployed system may fail to collect data in an accurate, complete, and timely manner due to such errors. If the network produces incorrect data, the resulting decisions on the data may be incorrect, and negatively impact the application. Hence, it is important to detect and diagnose these faults through run-time observation. Existing technologies face difficulty with wireless sensor networks due to the large scale of the networks, the resource constraints of bandwidth and energy on the sensing nodes, and the unreliability of the observation channels for recording the behavior. This paper presents a semi-automatic approach named H-SEND (hierarchical sensor network debugging) to observe the health of a sensor network and to remotely repair errors by reprogramming through the wireless network. In H-SEND, a programmer specifies correctness properties of the protocol ("invariants"). These invariants are associated with conditions (the "observed variables") of individual nodes or the network. The compiler automatically inserts checking code to ensure that the observed variables satisfy the invariants. The checking can be done locally or remotely, depending on the nature of the invariant. In the latter case, messages are generated automatically. If an error is detected at run-time, the logs of the observed variables are examined to analyze and correct the error. After errors are corrected, new programs or patches can be uploaded to the nodes through the wireless network. We construct a prototype to demonstrate the benefit of run-time detection and correction
62173532
Efficient interprocedural analysis for program parallelization and restructuring
An approach to efficient interprocedural analysis for program parallelization and restructuring is presented. Such analysis is needed for parallelizing loops which contain procedure calls. Our approach captures call effect on data dependencies by propagating the precise information of array subscripts from the called procedure. This allows the optimizing compiler to choose an efficient yet precise data dependence test scheme depending on the complexity of array reference patterns. The other existing methods do not provide such flexibility, hence may suffer from either imprecision or inefficiency. The paper also discusses usage of classical summary information in several important transformations for program parallelization. Experimental results are reported.
13022636
A Neural Model of Contour Integration in the Primary Visual Cortex
Experimental observations suggest that contour integration may take place in V1. However, there has yet to be a model of contour integration that uses only known V1 elements, operations, and connection patterns.This article introduces such a model, using orient ation selective cells, local cortical circuits, and horizontal intracortical connections. The model is composed of recurrently connected excitatory neurons and inhibitory interneurons, receiving visual input via oriented receptive fields resembling those found in primary visual cortex. Intracortical interactions modify initial activity patterns from input, selectively amplifying the activities of edges that form smooth contours in the image. The neural activities produced by such interactions are oscillatory and edge segments within a contour oscillate in synchrony. It is shown analytically and empirically that the extent of contour enhancement and neural synchrony increases with the smoothness, length, and closure of contours, as observed in experiments on some of these phenomena. In addition, the model incorporates a feedback mechanism that allows higher visual centers selectively to enhance or suppress sensitivities to given contours, effectively segmenting one from another. The model makes the testable prediction that the horizontal cortical connections are more likely to target excitatory (or inhibitory) cells when the two linked cells have their preferred orientation aligned with (or orthogonal to) their relative receptive field center displacements.