Finding out reasonable structures from bulky data is one of the difficulties in modeling of Bayesian network （BN）, which is also necessary in promoting the application of BN. This pa- per proposes an immune algorith...Finding out reasonable structures from bulky data is one of the difficulties in modeling of Bayesian network （BN）, which is also necessary in promoting the application of BN. This pa- per proposes an immune algorithm based method （BN-IA） for the learning of the BN structure with the idea of vaccination. Further- more, the methods on how to extract the effective vaccines from local optimal structure and root nodes are also described in details. Finally, the simulation studies are implemented with the helicopter convertor BN model and the car start BN model. The comparison results show that the proposed vaccines and the BN-IA can learn the BN structure effectively and efficiently.展开更多
A new method to evaluate the fitness of the Bayesian networks according to the observed data is provided. The main advantage of this criterion is that it is suitable for both the complete and incomplete cases while th...A new method to evaluate the fitness of the Bayesian networks according to the observed data is provided. The main advantage of this criterion is that it is suitable for both the complete and incomplete cases while the others not. Moreover it facilitates the computation greatly. In order to reduce the search space, the notation of equivalent class proposed by David Chickering is adopted. Instead of using the method directly, the novel criterion, variable ordering, and equivalent class are combined,moreover the proposed mthod avoids some problems caused by the previous one. Later, the genetic algorithm which allows global convergence, lack in the most of the methods searching for Bayesian network is applied to search for a good model in thisspace. To speed up the convergence, the genetic algorithm is combined with the greedy algorithm. Finally, the simulation shows the validity of the proposed approach.展开更多
为了挖掘多模态信息潜在的同构语义关系,并学习更好的项目表示,提出一种语义图增强多模态推荐(SGEMR)算法。首先,利用辅助的多模态信息补充历史的用户-项目交互,捕捉用户在不同模态下的偏好;然后,基于度量学习将松散的项目序列重新构建...为了挖掘多模态信息潜在的同构语义关系,并学习更好的项目表示,提出一种语义图增强多模态推荐(SGEMR)算法。首先,利用辅助的多模态信息补充历史的用户-项目交互,捕捉用户在不同模态下的偏好;然后,基于度量学习将松散的项目序列重新构建为紧密的项目-项目语义图,并设计一个语义层级注意力机制,融合项目的多模态信息;同时,提出一个图重构损失函数,使项目表示保留更多的语义关系,从而提高推荐性能。实验结果表明,在3个真实的数据集上与最优基线算法FREEDOM(FREEzes the item-item graph and DenOises the user-item interaction graph simultaneously for Multimodal recommendation)相比,所提算法的Recall@10分别提升了6.70%、11.30%、5.09%,NDCG@10分别提升了9.09%、12.73%、7.62%,并通过多个消融实验,验证了所提算法的有效性。展开更多
How to improve the efficiency of exact learning of the Bayesian network structure is a challenging issue.In this paper,four different causal constraints algorithms are added into score calculations to prune possible p...How to improve the efficiency of exact learning of the Bayesian network structure is a challenging issue.In this paper,four different causal constraints algorithms are added into score calculations to prune possible parent sets,improving state-ofthe-art learning algorithms’efficiency.Experimental results indicate that exact learning algorithms can significantly improve the efficiency with only a slight loss of accuracy.Under causal constraints,these exact learning algorithms can prune about 70%possible parent sets and reduce about 60%running time while only losing no more than 2%accuracy on average.Additionally,with sufficient samples,exact learning algorithms with causal constraints can also obtain the optimal network.In general,adding max-min parents and children constraints has better results in terms of efficiency and accuracy among these four causal constraints algorithms.展开更多
贝叶斯网络结构学习是贝叶斯网络推理及应用的基础.搜索高质量的节点序是贝叶斯网络结构学习的一类重要方法.针对在节点序空间中,搜索高质量节点序存在的难以高效、准确评估解的问题,本文提出了一种近似图引导的演化贝叶斯网络结构学习...贝叶斯网络结构学习是贝叶斯网络推理及应用的基础.搜索高质量的节点序是贝叶斯网络结构学习的一类重要方法.针对在节点序空间中,搜索高质量节点序存在的难以高效、准确评估解的问题,本文提出了一种近似图引导的演化贝叶斯网络结构学习算法.首先,该算法利用互信息构建无向近似图;其次,该算法通过结合节点序和无向近似图构造有向图结构,将其贝叶斯信息准则评分作为节点序的适应度来高效评估节点序,并在演化优化的框架下,使用提出的基于Kendall Tau Distance的交叉算子和基于逆度的变异算子搜索最优节点序;最后,将搜索到的最优节点序输入K2算法得到其对应的贝叶斯网络结构.在4种不同规模网络上的实验结果表明,该算法在收敛时间和准确度之间取得了较好的平衡,其评分相较于对比算法中的次优解分别提升了10.91%、12.28%、53.96%、10.87%.展开更多
贝叶斯网络是目前不确定知识表达和推理领域最有效的理论模型之一,利用贝叶斯网络进行分析和推理前首先需要通过结构学习和参数学习获取其网络模型,其中结构学习是参数学习的基础。针对现有萤火虫算法不符合生物学规则以及学习贝叶斯网...贝叶斯网络是目前不确定知识表达和推理领域最有效的理论模型之一,利用贝叶斯网络进行分析和推理前首先需要通过结构学习和参数学习获取其网络模型,其中结构学习是参数学习的基础。针对现有萤火虫算法不符合生物学规则以及学习贝叶斯网络结构存在效率低、容易陷入局部最优等问题,设计了一种基于互信息与性别机制的萤火虫算法(firefly algorithm based on mutual information and gender mechanism,MGM-FA)。首先,通过计算节点互信息得到贝叶斯网络骨架图,基于骨架图驱动MGM-FA算法生成初始种群;其次,引入基于性别机制的个性化贝叶斯网络种群更新策略,以保障贝叶斯网络个体的多样性;最后,引入局部优化器和扰动操作符,增强算法的寻优能力。分别在不同规模的标准网络上进行仿真实验,与现有同类型算法相比,该算法精度和效率均有所提升。展开更多
构建了系列球形中空结构的纳米线(NW),采用分子动力学(MD)对每个模型300个不同初始态的样本开展拉伸形变模拟。并利用基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)机器学习算法,...构建了系列球形中空结构的纳米线(NW),采用分子动力学(MD)对每个模型300个不同初始态的样本开展拉伸形变模拟。并利用基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)机器学习算法,获得了初始滑移面的位置。基于大数据统计,分析了初始滑移位置分布以及断裂位置分布两者之间的相关性。研究结果表明:当内部中空半径较小时,断裂位置分布形成于塑性形变阶段,初始滑移分布与断裂位置分布之间无显著的相关性;但是对于脆性特征明显的大中空半径的NW,高能内表面诱导产生的滑移面迅速积累,产生颈缩并导致最终的断裂。因此当内部中空结构达到一定尺寸时初始滑移位置的分布与最终断裂位置的分布之间有明确的因果关系。展开更多
基金supported by the National Natural Science Foundation of China(7110111671271170)+1 种基金the Program for New Century Excellent Talents in University(NCET-13-0475)the Basic Research Foundation of NPU(JC20120228)
文摘Finding out reasonable structures from bulky data is one of the difficulties in modeling of Bayesian network （BN）, which is also necessary in promoting the application of BN. This pa- per proposes an immune algorithm based method （BN-IA） for the learning of the BN structure with the idea of vaccination. Further- more, the methods on how to extract the effective vaccines from local optimal structure and root nodes are also described in details. Finally, the simulation studies are implemented with the helicopter convertor BN model and the car start BN model. The comparison results show that the proposed vaccines and the BN-IA can learn the BN structure effectively and efficiently.
基金This project was supported by the National Natural Science Foundation of China (70572045).
文摘A new method to evaluate the fitness of the Bayesian networks according to the observed data is provided. The main advantage of this criterion is that it is suitable for both the complete and incomplete cases while the others not. Moreover it facilitates the computation greatly. In order to reduce the search space, the notation of equivalent class proposed by David Chickering is adopted. Instead of using the method directly, the novel criterion, variable ordering, and equivalent class are combined,moreover the proposed mthod avoids some problems caused by the previous one. Later, the genetic algorithm which allows global convergence, lack in the most of the methods searching for Bayesian network is applied to search for a good model in thisspace. To speed up the convergence, the genetic algorithm is combined with the greedy algorithm. Finally, the simulation shows the validity of the proposed approach.
文摘为了挖掘多模态信息潜在的同构语义关系,并学习更好的项目表示,提出一种语义图增强多模态推荐(SGEMR)算法。首先,利用辅助的多模态信息补充历史的用户-项目交互,捕捉用户在不同模态下的偏好;然后,基于度量学习将松散的项目序列重新构建为紧密的项目-项目语义图,并设计一个语义层级注意力机制,融合项目的多模态信息;同时,提出一个图重构损失函数,使项目表示保留更多的语义关系,从而提高推荐性能。实验结果表明,在3个真实的数据集上与最优基线算法FREEDOM(FREEzes the item-item graph and DenOises the user-item interaction graph simultaneously for Multimodal recommendation)相比,所提算法的Recall@10分别提升了6.70%、11.30%、5.09%,NDCG@10分别提升了9.09%、12.73%、7.62%,并通过多个消融实验,验证了所提算法的有效性。
基金supported by the National Natural Science Foundation of China(61573285).
文摘How to improve the efficiency of exact learning of the Bayesian network structure is a challenging issue.In this paper,four different causal constraints algorithms are added into score calculations to prune possible parent sets,improving state-ofthe-art learning algorithms’efficiency.Experimental results indicate that exact learning algorithms can significantly improve the efficiency with only a slight loss of accuracy.Under causal constraints,these exact learning algorithms can prune about 70%possible parent sets and reduce about 60%running time while only losing no more than 2%accuracy on average.Additionally,with sufficient samples,exact learning algorithms with causal constraints can also obtain the optimal network.In general,adding max-min parents and children constraints has better results in terms of efficiency and accuracy among these four causal constraints algorithms.
文摘贝叶斯网络结构学习是贝叶斯网络推理及应用的基础.搜索高质量的节点序是贝叶斯网络结构学习的一类重要方法.针对在节点序空间中,搜索高质量节点序存在的难以高效、准确评估解的问题,本文提出了一种近似图引导的演化贝叶斯网络结构学习算法.首先,该算法利用互信息构建无向近似图;其次,该算法通过结合节点序和无向近似图构造有向图结构,将其贝叶斯信息准则评分作为节点序的适应度来高效评估节点序,并在演化优化的框架下,使用提出的基于Kendall Tau Distance的交叉算子和基于逆度的变异算子搜索最优节点序;最后,将搜索到的最优节点序输入K2算法得到其对应的贝叶斯网络结构.在4种不同规模网络上的实验结果表明,该算法在收敛时间和准确度之间取得了较好的平衡,其评分相较于对比算法中的次优解分别提升了10.91%、12.28%、53.96%、10.87%.
文摘贝叶斯网络是目前不确定知识表达和推理领域最有效的理论模型之一,利用贝叶斯网络进行分析和推理前首先需要通过结构学习和参数学习获取其网络模型,其中结构学习是参数学习的基础。针对现有萤火虫算法不符合生物学规则以及学习贝叶斯网络结构存在效率低、容易陷入局部最优等问题,设计了一种基于互信息与性别机制的萤火虫算法(firefly algorithm based on mutual information and gender mechanism,MGM-FA)。首先,通过计算节点互信息得到贝叶斯网络骨架图,基于骨架图驱动MGM-FA算法生成初始种群;其次,引入基于性别机制的个性化贝叶斯网络种群更新策略,以保障贝叶斯网络个体的多样性;最后,引入局部优化器和扰动操作符,增强算法的寻优能力。分别在不同规模的标准网络上进行仿真实验,与现有同类型算法相比,该算法精度和效率均有所提升。
文摘构建了系列球形中空结构的纳米线(NW),采用分子动力学(MD)对每个模型300个不同初始态的样本开展拉伸形变模拟。并利用基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)机器学习算法,获得了初始滑移面的位置。基于大数据统计,分析了初始滑移位置分布以及断裂位置分布两者之间的相关性。研究结果表明:当内部中空半径较小时,断裂位置分布形成于塑性形变阶段,初始滑移分布与断裂位置分布之间无显著的相关性;但是对于脆性特征明显的大中空半径的NW,高能内表面诱导产生的滑移面迅速积累,产生颈缩并导致最终的断裂。因此当内部中空结构达到一定尺寸时初始滑移位置的分布与最终断裂位置的分布之间有明确的因果关系。
