Maryam Fahimi - Department of Computer Engineering Mashhad Branch, Islamic Azad University Mashhad, Iran
Majid Vafaei Jahan - Department of Computer Engineering Mashhad Branch, Islamic Azad University Mashhad, Iran
Masood Niazi Torshiz - Department of Computer Engineering Mashhad Branch, Islamic Azad University Mashhad, Iran

With rise of web 2.0, its associated user-centric applications have attracted a lot of users. Folksonomy plays an important role in these systems, which is made of labeling data.Discovery triadic frequent closed patterns is an important tool in knowledge discovery in folksonomy. The huge volume of data andthe number of dimensions in these systems, including users, tags and resources are challenging for data mining. In this paper, amethod for discovering all triadic frequent closed patterns based on Hidden Markov Model in folksonomy is proposed. By extracting useful data from dataset, the proposed methodemprises to build Hidden Markov Model on the two dimensions, then with inference from created hidden model discover triadicfrequent closed patterns through applying third dimension on the results. In fact, extracting useful data in the first step and usingviterbi based algorithm, for inference, regularly are pruneddataset and are causes for triadic frequent closed patterns to be discovered more quickly. Testing on a real data set taken from Del.icio.us website and comparing the results with the same algorithm in the field of folksonomy called Trias show that the proposed method in terms of the time, can extract all triadic frequent closed patterns more effectively