基于GATS贝叶斯网络结构学习的航班延误模型

对遗传算法（GA）贝叶斯网络（BN）结构学习和禁忌搜索算法（TS）进行分析,提出遗传禁忌搜索贝叶斯网络结构学习算法GATS_BNSL。把禁忌搜索思想引入到遗传算法BN结构学习由父代种群产生后代种群的演化过程中,以禁忌搜索交叉和禁忌搜索变异改进传统的遗传算子,对比实验分析表明了GATS_BNSL的学习优势。应用此方法,基于真实数据,建立了大型枢纽机场航班离港延误模型。该模型切实反映了导致航班延误的多因素之间的因果关系,而且建模时间少,学习正确率高。     

一种求解最优路径的改进遗传算法

在应用遗传算法进行路径规划时,本文针对遗传算法的＂收敛盲目性＂和＂收敛速度慢＂两个难题,结合模拟退火算法对适应度函数进行改进,结合禁忌搜索对变异算子进行改进,并且在进化过程中使用改进的自适应方法调节交叉概率与变异概率。算法的分析和测试表明,本文算法的改进是有效的。     

基于无约束优化和遗传算法的贝叶斯网络结构学习方法

基于无约束优化和遗传算法,提出一种学习贝叶斯网络结构的限制型遗传算法.首先构造一无约束优化问题,其最优解对应一个无向图.在无向图的基础上,产生遗传算法的初始种群,并使用遗传算法中的选择、交叉和变异算子学习得到最优贝叶斯网络结构.由于产生初始种群的空间是由一些最优贝叶斯网络结构的候选边构成,初始种群具有很好的性质.与直接使用遗传算法学习贝叶斯网络结构的效率相比,该方法的学习效率相对较高.     

一种改进的贝叶斯网弧定向算法研究

贝叶斯网络是用来表示变量集合概率分布的图形模式,它提供了一种方便地表示概率信息的方法,它可以表示因果关系,但并不局限于因果关系。贝叶斯网对不确定性问题有很强的推理能力,近几年来受到众多研究者的重视。贝叶斯网络中弧的定向是指在已经有了变量之间的依赖关系图的条件下确定变量之间的边的方向的过程。介绍了一种改进了贝叶斯网弧定向的方法,该方法结合了目前多种定向方法的优点,实验证明该算法优于已存在的弧定向方法。     

基于推理信息量的BN参数学习变量离散化方法

提出推理信息量的概念,将其作为贝叶斯网络连续变量离散化评价标准。在连续变量离散化的过程中,采用遗传算法寻求最优解,设计个体编码方式、交叉算子和变异算子,将推理信息量作为衡量个体适应度的标准。实例分析证明,通过该方法对变量进行离散化后学习得到的贝叶斯网络在推理时能得到更大的推理信息量。     

基于Petri网与GA算法的FMS调度优化

提出了一种应用遗传算法解决柔性制造系统调度优化问题的新方法．首先用Petri网对柔性制造系统进行建模,然后应用遗传算法对该模型进行调度并获取近似最优解．在该算法中,用Petri网模型的激发序列作为染色体,采用期望值方法作为选择算子,总加工时间作为适应度函数,两点交叉法作为交叉算子,交叉点选择能到达相同标记的转移．对于变异算子,首先从染色体上随机选择一点作为变异点,然后从这点开始应用变异算法,该变异算法类似于Petri网的可达树算法．由于算法中的选择、交叉和变异算子都是对．Petri网模型中的元素进行操作,与问题空间中的元素无关,因此,与其它调度算法相比,它有较高的通用性．既可以处理典型的Job—Shop问题,也可以处理小批量、多品种的FMS(Flexible Manufacturing System)调度问题．文中通过实验验证了算法的有效性。     

一种求解旅行商问题的贪婪边重组交叉算子

提出了一种新的求解旅行商问题的贪婪边重组交叉算子。该交叉算子吸取了边重组交叉算子的优点,使得父代在进化过程中获得的优良的边能顺利地遗传给子代。同时,在边重组的过程中,该交叉算子引入所求旅行商问题的具体信息以指导新边的生成,从而该交叉算子具有贪婪特征。实验结果表明:对于简单的旅行商问题,贪婪边重组交叉算子能显著提高算法效率;对于大规模的旅行商问题,该交叉算子的效果也较理想。     

基于云遗传退火的贝叶斯网络结构学习算法

针对贝叶斯网络结构学习对算法高效性的要求,提出将云遗传算法和模拟退火算法相结合的云遗传模拟退火算法,以云遗传算法的选择、云交叉和云变异来完成模拟退火算法中的更新解操作;同时,针对算法在特定条件下陷入早熟收敛的问题,提出了改进的云交叉算子和云变异算子。仿真实验结果表明,所提云遗传模拟退火算法能有效提高贝叶斯网络学习的效率和准确性。     

一种优化神经网络结构的遗传禁忌算法

常用的神经网络是通过固定的网络结构得到最优权值，使网络的实用性受到影响。引入一种基于方向的交叉算子和禁忌变异算子，同时把禁忌算法(TS)引入标准遗传算法，结合标准遗传算法和禁忌算法的优点，提出一种优化神经网络结构的遗传禁忌混合算法，实现了网络结构和权值同时优化。仿真实验表明，与遗传算法和禁忌算法相比，该算法优化的神经网络收敛速度较快、预测精度较高，提高了网络的处理能力。     

用一种含启发式变异策略的遗传算法求解TSP

通过分析TSP问题的特征,结合以减少周游路线中交叉边为启发式信息,引入了一个遗传算法中新的变异策略用于TSP求解。对新策略的有效性进行了证明并且给出了具体的实现方案,同时通过TSP Lib上的测试样例将该启发式变异算子和另外两个传统的变异算子(插入式变异和交换式变异)进行了比较。比较结果表明了新变异策略具有更大的优势。     

基于类约束的贝叶斯网络分类器学习

分类能力是人类经过学习得到的重要而基本的能力，也是机器学习、模式识别和数据采掘研究的核心问题．在01损失率下，证明了基于类约束的贝叶斯网络分类器是最优分类器．建立该分类器的核心问题是基于类约束属性贝叶斯网络结构学习，给出了学习属性贝叶斯网络结构的方法，在学习过程中使用了根据弧方向因果语义确定边方向的方法，并和碰撞识别定向相结合，在边定向之后进行冗余弧检验，解决了目前冗余边检验在定向之前所导致的问题，显著提高了结构学习效率和准确性．并使用模拟数据进行了分类实验和分析。     

基于评分函数的贝叶斯网络结构融合算法

利用贝叶斯网络进行因果关系推理已广泛应用于人工智能领域。基于约束方法从观测数据中构建贝叶斯网络通常得到的是其马尔科夫等价类，因存在无向边而无法进行有效的因果推断。为此，基于贝叶斯网络评分函数，并结合集成学习提出了一种模型融合算法，通过对不同的网络结构加权融合，以减少网络中无向边的个数，进而提高其可推断性。实验结果表明，不仅显著减少了无向边条数，也提高了最终网络结构的学习效果，验证了算法的有效性。     

基于先验节点序学习贝叶斯网络结构的优化方法

针对小样本数据集下学习贝叶斯网络 (Bayesian networks, BN)结构的不足, 以及随着条件集的增大, 利用统计方法进行条件独立 (Conditional independence, CI) 测试不稳定等问题, 提出了一种基于先验节点序学习网络结构的优化方法. 新方法通过定义优化目标函数和可行域空间, 首次将贝叶斯网络结构学习问题转化为求解目标函数极值的数学规划问题, 并给出最优解的存在性及唯一性证明, 为贝叶斯网络的不断扩展研究提出了新的方案. 理论证明以及实验结果显示了新方法的正确性和有效性.     

Learning Bayesian networks for discrete data

Bayesian networks have received much attention in the recent literature. In this article, we propose an approach to learn Bayesian networks using the stochastic approximation Monte Carlo (SAMC) algorithm. Our approach has two nice features. Firstly, it possesses the self-adjusting mechanism and thus avoids essentially the local-trap problem suffered by conventional MCMC simulation-based approaches in learning Bayesian networks. Secondly, it falls into the class of dynamic importance sampling algorithms; the network features can be inferred by dynamically weighted averaging the samples generated in the learning process, and the resulting estimates can have much lower variation than the single model-based estimates. The numerical results indicate that our approach can mix much faster over the space of Bayesian networks than the conventional MCMC simulation-based approaches.     

Understanding the scalability of Bayesian network inference using clique tree growth curves

One of the main approaches to performing computation in Bayesian networks (BNs) is clique tree clustering and propagation. The clique tree approach consists of propagation in a clique tree compiled from a BN, and while it was introduced in the 1980s, there is still a lack of understanding of how clique tree computation time depends on variations in BN size and structure. In this article, we improve this understanding by developing an approach to characterizing clique tree growth as a function of parameters that can be computed in polynomial time from BNs, specifically: (i) the ratio of the number of a BN's non-root nodes to the number of root nodes, and (ii) the expected number of moral edges in their moral graphs. Analytically, we partition the set of cliques in a clique tree into different sets, and introduce a growth curve for the total size of each set. For the special case of bipartite BNs, there are two sets and two growth curves, a mixed clique growth curve and a root clique growth curve. In experiments, where random bipartite BNs generated using the BPART algorithm are studied, we systematically increase the out-degree of the root nodes in bipartite Bayesian networks, by increasing the number of leaf nodes. Surprisingly, root clique growth is well-approximated by Gompertz growth curves, an S-shaped family of curves that has previously been used to describe growth processes in biology, medicine, and neuroscience. We believe that this research improves the understanding of the scaling behavior of clique tree clustering for a certain class of Bayesian networks; presents an aid for trade-off studies of clique tree clustering using growth curves; and ultimately provides a foundation for benchmarking and developing improved BN inference and machine learning algorithms.     

Encoding probability propagation in belief networks

Complexity reduction is an important task in Bayesian networks. Recently, an approach known as the linear potential function (LPF) model has been proposed for approximating Bayesian computations. The LPF model can effectively compress a conditional probability table into a linear function. This correspondence extends the LPF model to approximate propagation in Bayesian networks. The extension focuses on encoding probability propagation as a polynomial function for a class of tractable problems.     

基于TAN贝叶斯网络分类器的测井岩性预测

贝叶斯网络是一种建立在概率和统计理论基础上的数据分析和辅助决策工具,利用其构造出的树扩展朴素贝叶斯网络分类器是目前最优秀的分类器之一。针对石油勘探中测井数据的特殊性,利用贝叶斯网络预测出其对应的岩性,并介绍了使用此方法进行岩性预测的算法过程。通过BNT软件包用Matlab语言构建了分类器,并由实验结果的分析说明了此分类器的优点。     

BIC-based node order learning for improving Bayesian network structure learning

Node order is one of the most important factors in learning the structure of a Bayesian network (BN) for probabilistic reasoning. To improve the BN structure learning, we propose a node order learning algorithmbased on the frequently used Bayesian information criterion (BIC) score function. The algorithm dramatically reduces the space of node order and makes the results of BN learning more stable and effective. Specifically, we first find the most dependent node for each individual node, prove analytically that the dependencies are undirected, and then construct undirected subgraphs U_G. Secondly, the U_G- is examined and connected into a single undirected graph U_GC. The relation between the subgraph number and the node number is analyzed. Thirdly, we provide the rules of orienting directions for all edges in UGC, which converts it into a directed acyclic graph (DAG). Further, we rank the DAG’s topology order and describe the BIC-based node order learning algorithm. Its complexity analysis shows that the algorithm can be conducted in linear time with respect to the number of samples, and in polynomial time with respect to the number of variables. Finally, experimental results demonstrate significant performance improvement by comparing with other methods.     

Some issues of designing genetic algorithms for traveling salesman problems

This paper demonstrates that a robust genetic algorithm for the traveling salesman problem (TSP) should preserve and add good edges efficiently, and at the same time, maintain the population diversity well. We analyzed the strengths and limitations of several well-known genetic operators for TSPs by the experiments. To evaluate these factors, we propose a new genetic algorithm integrating two genetic operators and a heterogeneous pairing selection. The former can preserve and add good edges efficiently and the later will be able to keep the population diversity. The proposed approach was evaluated on 15 well-known TSPs whose numbers of cities range from 101 to 13509. Experimental results indicated that our approach, somewhat slower, performs very robustly and is very competitive with other approaches in our best surveys. We believe that a genetic algorithm can be a stable approach for TSPs if its operators can preserve and add edges efficiently and it maintains population diversity.     

一种基于决策图贝叶斯网络的强度Pareto进化算法

提出了一种基于决策图贝叶斯网络的强度Pareto进化算法,该算法把贝叶斯概率模型结合到多目标进化算法中,通过构造和学习网络来替代传统进化算法中的交叉重组和变异等遗传操作,避免对大量参数的人工设置和重要构造块的破坏．求解多目标背包问题的仿真结果表明,所提算法可以快速收敛到较好的Pareto前沿,有很强的鲁棒性．