图 书 馆
网页的时间快照，一个原则性的方法Robust Web Extraction, A Principled Approach |
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| 课程网址: | http://videolectures.net/akbc2010_bohannon_rwepa/ |
| 主讲教师: | Philip Bohannon |
| 开课单位: | 雅虎公司 |
| 开课时间: | 信息不详。欢迎您在右侧留言补充。 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | On script-generated web sites, many documents share common HTML tree structure, allowing wrappers to effectively extract information of interest. Of course, the scripts and thus the tree structure evolve over time, causing wrappers to break repeatedly, and resulting in a high cost of maintaining wrappers. In this paper, we explore a novel approach: we use temporal snapshots of web pages to develop a tree-edit model of HTML, and use this model to improve wrapper construction. We view the changes to the tree structure as suppositions of a series of edit operations: deleting nodes, inserting nodes and substituting labels of nodes. The tree structures evolve by choosing these edit operations stochastically. Our model is attractive in that the probability that a source tree has evolved into a target tree can be estimated efficiently -- in quadratic time in the size of the trees -- making it a potentially useful tool for a variety of tree-evolution problems. We give an algorithm to learn the probabilistic model from training examples consisting of pairs of trees, and apply this algorithm to collections of web-page snapshots to derive HTML-specific tree edit models. Finally, we describe a novel wrapper-construction framework that takes the tree-edit model into account, and compare the quality of resulting wrappers to that of traditional wrappers on synthetic and real HTML document examples. |
| 关 键 词: | 网页; 原则性方法 |
| 课程来源: | 视频讲座网 |
| 最后编审: | 2020-01-13：chenxin |
| 阅读次数: | 41 |