Introduction
Social tagging system is an application which provides a function of marking labels for web users. With the prevalence of web2.0, content-sharing websites of which social tagging mechanism is a key part develop rapidly. The mechanism transfers the right of categorizing internet resources from specialists to common persons. Users can freely provide metadata to describe the content of resource on the Internet so as to organize the resource easily and share with their friends conveniently. There are several typical websites with tagging systems, such as Delicious with publications.
Personalized tag recommendation [] is the main part in a tagging system. The systems predict and offer users a set of tags that they are most likely to use. Users tagging behaviors can be seen as ternary relations
. When a Tag t is recommended for a User u to annotate Item i , t should be highly relevant to both u and i . For the reason that different users have diverse ways of tagging, recommended tags should differ from user to user. At the same time, the tags should be able to describe the content of items.
Our work builds on the personalized tag recommender method by using Random Walk model. Methods based on Random Walk like Random Walk with Restart (RWR) [] have shown to result in good prediction quality. But the sparsity problem still exists in graph, which limit the prediction quality. Here, we introduce association rules into Random Walk, in order to acquire more semantic information in the graph.
In this paper, our contributions are summarized as follows:
Building a new model (Association Rule based Rand Walk) for personalized tag recommendation.
Conducting experiments on the real-world dataset and demonstrating that our model outperforms other models based on Random Walk.
Our method can alleviate the problem of sparsity.
The rest of this paper is organized as follows. In the next section, we review and discuss the related work. Then, in Sect..
Related Work
Personalized tag recommendation is a hot topic in recommender system over the years. Different types of tagging systems were detailed by Huberman et al. []. In general, according to whether the processing procedure involves the resource content, tag recommendation methods fall into two categories: content-based approaches and graph-based approaches.
Content-based methods, which usually collect available information from context of items (e.g., web pages, anchor text, academic papers or other textual resources) to build user models or item models, can predict tags even for cold start. Yin [] proposed a Bayesian probabilistic model, the prediction is treated as the reverse of web search, consider a list of words on web pages as a list of tags, then retrieve the potential tags for the given web page.
Liu et al. [] put forward a fast tag recommending framework named Feature-Driven Tagging which represents a tag by some features. The feature can be a word, an id or other context information. Content-based approaches usually result in better precision than non-content-based approaches in most cases because of the more information ultilized by the former. However, content-based methods are unavailable where items belong to nonstructural resources or the content can not be obtained directly, such as movies, songs, etc.
Graph-based methods, which focus on the relations between users, items and tags, mostly yield lower computation complexity compared with content-based methods, for they dont parse items content. Adriana et al. [] extended Latent Dirichlet Allocation for recommending tags, which is on the hypothesis that item content consists of some latent topics. When a topic is represented by a tag probability distribution, tags can be predicted according to the posterior probability of latent topics.
There are many methods based on Factorization models. Higher-Order-Singular-Value-Decomposition (HOSVD) was introduced into tag recommendation to reduce tensor dimensionality in [] put forward a special Tucker Decomposition model called Pairwise Interaction Tensor Factorization (PITF) with linear runtime for learning and prediction. On their experiment dataset, the run time of PITF is shorter than TD, and the former can get better prediction as well. Since methods based on Factorization are quite complex, they are hardly applied to real systems.
In the fields of item recommendation like e-commerce, movie, music or photo websites, collaborative filtering [] introduced collaborative filtering into tag recommendation.
There were some models considering tag recommendation from other perspectives. Jin [].
Definition
When users are marking labels to items, tag recommender systems will predict and offer some tags the users might use. The systems calculate target tags from users behavior history and item context.
Given a set of items I , tags T , and users U , we represent the users marking to items with the ternary relations
. For tag recommender, the task is to offer a specific pair (user,item) a list of tags. Here, we define distinct user-item pairs Ps :
. All methods presented in this paper, give a scoring function