AND-OR Tree Research Articles

Rateless coding transmission over multi-state dying erasure channel for SATCOM

Satellite communication (SATCOM) systems have attracted great attention from academic and industrial communities in recent years, and huge amount of data delivery over satellite downlinks is considered as a promising service in emerging 5G networks, such as multimedia broadcasting. Nevertheless, due to intermittent connections from LEO or MEO satellite to earth station, and high dynamic channel conditions over downlinks, satellites may not be able to transmit the large data files to the ground station on time. In this paper, we propose a new rateless coding transmission for multi-state dying erasure channels (MDEC) with random channel life span and time-varying packet error rates, to improve the transmitting capability over SATCOM downlinks. Firstly, a heuristic approach for suboptimal degree distributions based on AND-OR tree technique is presented to achieve higher intermediate performance and lower symbol error rate of our proposed rateless codes. Furthermore, the appropriate code length of the connective window is derived and analyzed for enhanced average throughput on MDEC that is also optimized by maximum problem solving. Simulations have been conducted to evaluate the effectiveness of our rateless coding transmission for large file delivery on dynamic channel conditions. The results demonstrate that our proposed transmission scheme outperforms existing conventional rateless codes with significantly better intermediate performance and throughput performance over unreliable SATCOM downlinks, under time-varying packet error rates and unpredictable occurrences of exhausted energy or cosmic ray attacks.

Optimal Design of a Reconfigurable Machine Tool Considering Machine Configurations and Configuration Changes

A reconfigurable machine tool (RMT) is used as a group of machines by changing its configurations for different machining functions such as milling and turning. An optimization approach is introduced in this research for the design of a RMT based on evaluations to both the different machine configurations and the reconfiguration processes to change between machine configurations. In this research, different design candidates, machine configurations for each design candidate, and parameters of the machine configurations are modeled by a generic design AND-OR tree based on design requirements. A specific design solution modeled by multiple machine configurations and their parameters is created from the generic design AND-OR tree by tree-based search. For each design solution, reconfiguration process to change from one machine configuration to another configuration is modeled by a generic process AND-OR graph that is composed of operation candidates, sequential constraints among operations and operation parameters. A specific process solution is created from the generic process AND-OR graph by graph-based search. A multi-level and multi-objective optimization method is developed to obtain the optimal design that is modeled by its machine configurations, parameters of machine configurations, reconfiguration processes to change between machine configurations, and parameters of reconfiguration processes. A case study is implemented to demonstrate the effectiveness of this new optimal RMT design approach.

A Bio-Inspired Integration Method for Object Semantic Representation

Abstract We have two motivations. Firstly, semantic gap is a tough problem puzzling almost all sub-fields of Artificial Intelligence. We think semantic gap is the conflict between the abstractness of high-level symbolic definition and the details, diversities of low-level stimulus. Secondly, in object recognition, a pre-defined prototype of object is crucial and indispensable for bi-directional perception processing. On the one hand this prototype was learned from perceptional experience, and on the other hand it should be able to guide future downward processing. Human can do this very well, so physiological mechanism is simulated here. We utilize a mechanism of classical and non-classical receptive field (nCRF) to design a hierarchical model and form a multi-layer prototype of an object. This also is a realistic definition of concept, and a representation of denoting semantic. We regard this model as the most fundamental infrastructure that can ground semantics. Here a AND-OR tree is constructed to record prototypes of a concept, in which either raw data at low-level or symbol at high-level is feasible, and explicit production rules are also available. For the sake of pixel processing, knowledge should be represented in a data form; for the sake of scene reasoning, knowledge should be represented in a symbolic form. The physiological mechanism happens to be the bridge that can join them together seamlessly. This provides a possibility for finding a solution to semantic gap problem, and prevents discontinuity in low-order structures.

Development of Adaptable Products Based on Modular Design and Optimization Methods

A new approach is introduced in this research to identify the optimal designs of adaptable products that can be changed, such as reconfigured and upgraded, in the operation stage considering the whole product life-cycle spans based on the modular design and optimization methods. In this new approach, product descriptions in different life-cycle phases are modeled by different configurations, and each of these configurations is described by a set of parameters. Components with similar life-cycle properties are grouped into modules. A hybrid AND-OR tree is used to model all feasible design candidates, different configurations in different life-cycle phases for each feasible design candidate, and parameters for each configuration. A multi-level optimization method is employed to identify the best design solution, its configurations in different life-cycle phases, and parameter values of the relevant configurations based on evaluation considering the whole product life-cycle span. A case study is implemented to demonstrate the effectiveness of the developed new adaptable design approach.

Generalized Unequal Error Protection Rateless Codes for Distributed Wireless Relay Networks

A generalization of unequal error protection (UEP) rateless codes and distributed rateless codes for distributed relay networks is proposed. We consider a two-hop relaying network where a single source transmits UEP rateless coded data to a destination via multiple relays. At the relays, the UEP rateless coded symbols are re-encoded by distributed rateless codes (DRC) to minimize the redundancy at the second hop. Previously introduced UEP rateless codes (URC) have supported a limited number of importance classes, mostly two classes, and targeted importance levels suited to a specific application. In this paper, however, we formulate an optimization problem to provide optimal URC in terms of the symbol error rate (SER) given any specific number and strengths of importance levels. Next, another optimization is proposed to obtain DRC with the minimum SER at a given overhead, which utilizes information of common symbols among the relays. The optimization methods are based on the AND-OR tree analysis and sequential quadratic programming. In addition, we evaluate the minimum achievable end-to-end symbol error rates over the wireless relay networks.

Learning 3D Object Templates by Quantizing Geometry and Appearance Spaces.

While 3D object-centered shape-based models are appealing in comparison with 2D viewer-centered appearance-based models for their lower model complexities and potentially better view generalizabilities, the learning and inference of 3D models has been much less studied in the recent literature due to two factors: i) the enormous complexities of 3D shapes in geometric space; and ii) the gap between 3D shapes and their appearances in images. This paper aims at tackling the two problems by studying an And-Or Tree (AoT) representation that consists of two parts: i) a geometry-AoT quantizing the geometry space, i.e. the possible compositions of 3D volumetric parts and 2D surfaces within the volumes; and ii) an appearance-AoT quantizing the appearance space, i.e. the appearance variations of those shapes in different views. In this AoT, an And-node decomposes an entity into constituent parts, and an Or-node represents alternative ways of decompositions. Thus it can express a combinatorial number of geometry and appearance configurations through small dictionaries of 3D shape primitives and 2D image primitives. In the quantized space, the problem of learning a 3D object template is transformed to a structure search problem which can be efficiently solved in a dynamic programming algorithm by maximizing the information gain. We focus on learning 3D car templates from the AoT and collect a new car dataset featuring more diverse views. The learned car templates integrate both the shape-based model and the appearance-based model to combine the benefits of both. In experiments, we show three aspects: 1) the AoT is more efficient than the frequently used octree method in space representation; 2) the learned 3D car template matches the state-of-the art performances on car detection and pose estimation in a public multi-view car dataset; and 3) in our new dataset, the learned 3D template solves the joint task of simultaneous object detection, pose/view estimation, and part localization. It can generalize over unseen views and performs better than the version5 of the DPM model in terms of object detection and semantic part localization.

A New Cross-Level Decoding Scheme for LT Codes

In this letter, we propose a new cross-level decoding method for LT codes, where the results of packet-level decoding are fed back to bit-level decoding to improve the overall decoding performance. Another advantage of our method is that it keeps the original LT decoder structure and does not require extra real field computation. We provide the revised And-Or Tree analysis for the proposed method and validate it with numerical simulations.

A Distributed LT Code Design for Multiple-Access Relay Networks Subject to Erasures

This letter proposes a new distributed Luby transform (LT) code which is particularly suitable for the multiple-access relay network with erasure channels. We analyze the asymptotic performance of our distributed coding scheme by virtue of AND-OR tree analysis and present the simulation results of finite length comparing with existing methodologies. The proposed coding scheme is shown to be superior to conventional strategies in presence of both source-relay and relay-sink erasures.

The Pattern Based Visual Property Specification Language and Supporting System for Software Verifications

This paper deals with issue of properties specification for software verifications and translation between formal languages. Through this paper, the unique framework of property specifications including most kinds of formal specifications logics, automatic methods are shown by a property specifications guided system and PVSL(The Pattern based Visual property Specification Language).Additionally, a properties to specify and structures, Interconnection of them are also described by property charts. In this study, the pattern based visual property specification language (PVSL) is defined and property specifications method is also designed by convenience specifications of required property.Required properties can be described by its charts and analyzes its meaning and structures as using patterns diagrams and property and-or tree. On the other hands, it also guarantees stability and limitation of utilizations of patterns using much stronger specifying Dwyer`s meaning based property classification. The PVSL and property charts use hierarchical state machine notation to take advantage of knowledge a person who is one of practitioners has as much as possible, and for Nu-SMV, CW-CNC. They can be adapted to describe property charts and analyze into examples of CTL(Computation Tree Logic) and Modal Mu-Calculus logic that have been already used.Keywords: Patterns, Property specifications, model checking, Software verification

An Algorithm for Generating Boolean Expressions in VHDL Based on Ladder Diagrams

This study proposes an algorithm for generating the associated Boolean expression in VHDL, given a ladder diagram (LD) as the input. The purpose of the algorithm is to implement of field-programmable gate array- (FPGA-) based programmable logic controllers (PLCs), where an effective conversion from an LD to its associated Boolean expressions seems rarely mentioned. Based on this core thought, the conversion process of the algorithm first involves abstracting and expressing the encountered LD as an activity-on-vertex (AOV) graph. Next, an AND-OR tree in which AND-nodes and OR-nodes connote the series and the parallel relationships between the vertices of the AOV graph is constructed based on the AOV graph. Therefore, by a traversal to the AND-OR tree, the associated Boolean expression, as the output of the algorithm, can be easily obtained in VHDL. The proposed algorithm is then verified with an illustrative example, wherein a complicated LD is given as the input.

The design and analysis of unequal error protection fountain coding for multiple source networks over binary erasure channels

A novel network model of multiple source fountain coding is developed and a novel class of generic multiple source fountain codes with unequal error protection (UEP) property is proposed. The And-Or tree analysis technique is generalized to analyze the asymptotic performance of the proposed codes and a joint optimization method employing both linear and nonlinear programs is developed to optimize the degree dis- tributions. Furthermore, we propose three basic methods to achieve UEP property and the performance of each method is discussed. We employ these analytical results and optimization method to design and discuss several UEP codes with two and four sources for different application scenarios. Simulation results verify that the proposed codes can be applied to the networks with any number of sources and can provide strong UEP property in various ways based on the proposed three basic methods.

The Design and Analysis of Distributed Fountain Codes in Three-Source Single-Relay Networks

A novel distributed fountain coding scheme for three-source single-relay networks is proposed. First, the robust Soliton distribution (RSD) is threefoldly deconvolved to get the degree distribution for each source performing encoding. Then the single relay performs re-encoding using certain degree distribution. The asymptotic performance of distributed fountain codes with three sources (DFC-3) is analyzed by the And-Or tree technique. Simulations of the proposed DFC-3 are evaluated and compared with other fountain coding schemes. Simulation results show that the overall degree distribution of DFC-3 is consistent with RSD, and the BER performance agrees with the results of asymptotic analysis. It also reveals that DFC-3 have good performance on lossless channels.

Animated Pose Templates for Modeling and Detecting Human Actions

This paper presents animated pose templates (APTs) for detecting short-term, long-term, and contextual actions from cluttered scenes in videos. Each pose template consists of two components: 1) a shape template with deformable parts represented in an And-node whose appearances are represented by the Histogram of Oriented Gradient (HOG) features, and 2) a motion template specifying the motion of the parts by the Histogram of Optical-Flows (HOF) features. A shape template may have more than one motion template represented by an Or-node. Therefore, each action is defined as a mixture (Or-node) of pose templates in an And-Or tree structure. While this pose template is suitable for detecting short-term action snippets in two to five frames, we extend it in two ways: 1) For long-term actions, we animate the pose templates by adding temporal constraints in a Hidden Markov Model (HMM), and 2) for contextual actions, we treat contextual objects as additional parts of the pose templates and add constraints that encode spatial correlations between parts. To train the model, we manually annotate part locations on several keyframes of each video and cluster them into pose templates using EM. This leaves the unknown parameters for our learning algorithm in two groups: 1) latent variables for the unannotated frames including pose-IDs and part locations, 2) model parameters shared by all training samples such as weights for HOG and HOF features, canonical part locations of each pose, coefficients penalizing pose-transition and part-deformation. To learn these parameters, we introduce a semi-supervised structural SVM algorithm that iterates between two steps: 1) learning (updating) model parameters using labeled data by solving a structural SVM optimization, and 2) imputing missing variables (i.e., detecting actions on unlabeled frames) with parameters learned from the previous step and progressively accepting high-score frames as newly labeled examples. This algorithm belongs to a family of optimization methods known as the Concave-Convex Procedure (CCCP) that converge to a local optimal solution. The inference algorithm consists of two components: 1) Detecting top candidates for the pose templates, and 2) computing the sequence of pose templates. Both are done by dynamic programming or, more precisely, beam search. In experiments, we demonstrate that this method is capable of discovering salient poses of actions as well as interactions with contextual objects. We test our method on several public action data sets and a challenging outdoor contextual action data set collected by ourselves. The results show that our model achieves comparable or better performance compared to state-of-the-art methods.

Distributed Raptor Coding for Erasure Channels: Partially and Fully Coded Cooperation

In this paper, we propose a new rateless coded cooperation scheme for a general multi-user cooperative wireless system. We develop cooperation methods based on Raptor codes with the assumption that the channels face erasure with specific erasure probabilities and transmitters have no channel state information. A fully coded cooperation (FCC) and a partially coded cooperation (PCC) strategy are developed to maximize the average system throughput. Both PCC and FCC schemes have been analyzed through AND-OR tree analysis and a linear programming optimization problem is then formulated to find the optimum degree distribution for each scheme. Simulation results show that optimized degree distributions can bring considerable throughput gains compared to existing degree distributions which are designed for point-to-point binary erasure channels. It is also shown that the PCC scheme outperforms the FCC scheme in terms of average system throughput.

Asymptotic Analysis and Optimization for Generalized Distributed Fountain Codes

A novel generic fountain coding scheme for multiple access networks over erasure channels is proposed and it can be applied to several instances. Moreover, asymptotic analysis using And-Or tree analysis technique is evaluated and an efficient joint optimization method employing linear and nonlinear programs is presented. Furthermore, selective distributed Luby Transform (SDLT) codes and unequal error protection (UEP) codes are evaluated as two special cases. Simulation results reveal that the proposed coding scheme can reduce decoding overhead and provide strong UEP property across sources.

APPROXIMATING THE AND-OR TREE

The approximate degree of a Boolean function f is the least degree of a real polynomial that approximates f within 1=3 at every point. We prove that the function V n i=1 W n j=1 xi j, known as the AND-OR tree, has approximate degree W(n). This lower bound is tight and closes a line of research on the problem, the best previous bound being W(n 0:75 ). More generally, we prove that the function V m=1 W n j=1 xi j has approximate degree W( p mn); which is tight. The same lower bound was obtained independently by Bun and Thaler (2013) using related techniques.

The Intersection of Two Halfspaces Has High Threshold Degree

The threshold degree of a Boolean function $f\!\!\,: \{0,1\}^n \rightarrow \{-1, +1\}$ is the least degree of a real polynomial $p$ such that $f(x)\equiv{{\rm sgn}\,p(x)}.$ We construct two halfspaces on $\{0,1\}^n$ whose intersection has threshold degree $\Theta(\sqrt n),$ an exponential improvement on previous lower bounds. This solves an open problem due to Klivans [A Complexity-Theoretic Approach to Learning, Ph.D. thesis, MIT, Cambridge, MA, 2002] and rules out the use of perceptron-based techniques for PAC learning the intersection of two halfspaces, a central unresolved challenge in computational learning. We also prove that the intersection of two majority functions has threshold degree $\Omega({\rm log}\,n),$ which is tight and settles a conjecture of O'Donnell and Servedio [Proceedings of the $35$th Annual ACM Symposium on Theory of Computing (STOC), 2003, pp. 325--334]. Our proof consists of two parts. First, we show that for any nonconstant Boolean functions $f$ and $g,$ the intersection $f(x)\wedge g(y)$ has threshold degree $O(d)$ if and only if $\|f-F\|_\infty + \|g-G\|_\infty < 1$ for some rational functions $F,$ $G$ of degree $O(d).$ Second, we determine the least degree required for approximating a halfspace and a majority function to any given accuracy by rational functions. Our technique further allows us to obtain direct sum theorems for polynomial representations of composed Boolean functions. In particular, we give an improved lower bound on the approximate degree of the AND-OR tree.

Distributed Unequal Error Protection Rateless Codes over Erasure Channels: A Two-Source Scenario

In distributed rateless coding, multiple disjoint sources need to deliver their rateless coded symbols (where a symbol may contain a single bit or thousands of bits) to a common destination via a single relay. In this paper, we propose and design novel distributed rateless codes called DU-rateless codes that can provide Unequal Error Protection (UEP) for disjoint sources with unequal data lengths on erasure channels. To design DU-rateless codes, we tune the coding parameters at each source and propose to smartly combine the encoded symbols at the relay. We analyze DU-rateless codes employing And-Or tree analysis technique and leverage our analysis to design several sets of codes for various setups employing the-state-of-the-art multi-objective genetic algorithms. We evaluate the performance of the designed codes using numerical simulations and discuss their advantages.

무선 네트워크 환경에서 효과적인 영상 스트리밍을 위한 And-Or 트리 기반의 LT 부호화 심볼 패킷화 알고리즘

본 논문에서는 무선 네트워크 환경에서의 패킷 손실에 따른 영상 스트리밍 서비스의 영상 열화를 최소화 시키는 And-Or 트리 기반의 LT 패킷화 알고리즘을 제안한다. 심볼들의 효율적인 패킷화를 위해 And-Or 트리를 통한 심볼들 간의 관계를 분석하고 이 관계를 바탕으로 LT 부호화 심볼들이 포함된 패킷들 간의 의존성을 줄여 패킷손실에 대한 영향을 최소화 시키는 패킷화 알고리즘을 설계한다. 마지막으로 무선 네트워크 환경에서 영상 스트리밍 시스템을 통해 제안한 패킷화 알고리즘이 기존의 패킷화 알고리즘보다 더 향상된 복호화 성능과 영상 화질을 제공할 수 있음을 보인다. In this paper, we propose a robust And-Or tree-based Luby transform encoded symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols are analyzed by using And-Or tree, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.

AND-OR tree-based mode selection for video coding

The conventional video coding approach is pragmatic in that researchers design different methods and compare their results to state-of-the-art methods. Although the H.264/AVC baseline is effective, there is a need to develop an abstract view of video coding, in the hope that new insights can be derived from the abstraction. In this paper, we propose a preliminary approach based on an AND-OR tree representation of video coding. We show that the H.264/AVC baseline can be represented as an AND-OR tree structure. Based on the AND-OR tree representation, we propose two video coding systems: one is a T+2D wavelet codec based on a motion-compensated temporal filtering (MCTF) lifting structure, and the other is the AND-OR tree implementation of the H.264/AVC baseline. We also compare the proposed systems’ coding performance in terms of the PSNR with that of H.264/AVC JM 16.2.