## 3 Semantic Educational Recommender Systems
### The SERS Approach
#### Algorithms 2011  
Bearing the features compiled in Table 2 in mind, three key issues are required in the SERS approach:  
* **A recommendation model** that supports the recommendation of actions on LMS objects (F3) and semantically characterizes the recommendations (F4) in order to bridge the gap between \begin{table}
\begin{tabular}{|p{113.8 pt}|p{56.9 pt}|p{56.9 pt}|p{56.9 pt}|} \hline
**Feature** & **IRS** & **SIRS** & **Comment** \\ \hline F1. Considers education criteria & yes & yes & A recommender system in the educational domain is bound to consider educational criteria directly or indirectly (_i.e._, in terms of context). \\ \hline F2. Recommends access to learning objects or courses & yes & yes & State of the art shows that recommender systems in the educational domain mainly recommend users to access learning objects or to enroll in courses. SERS extend the scope of the recommendations to other elements beyond learning objects and courses. \\ \hline F3. Recommends actions on any item in the LMS & no & yes & Since an LMS consists of items accessed through links, a recommendation in a SERS is a link to any LMS item. Moreover, some content goes with the link recommended, thus it can specify what action is to be done on the object linked. \\ \hline F4. Recommendations are semantically described through an explicit recommendation model that can be filled in by educators & no & yes & ERS apply algorithms to select the object to recommend but educators cannot provide knowledge to the recommendation process. In the SERS approach, the recommendation model allows educators to elicit knowledge, which can be used by the recommendation mechanism. \\ \hline F5. The web services that can be defined for the information exchange among the components follow the recommendation model & no & yes & Since there is no recommendation model in ERS, web services descriptions (defined to support software components interoperability) can only consider the technical information required for the communication process. In SERS, web services descriptions map the recommendation model. \\ \hline F6. Standards and specifications are considered when describing the recommendations & no & yes & ERS do not take advantage of the semantic descriptions provided by educational standards and specifications. In SERS, this is a distinctive feature. \\ \hline F7. Usability and accessibility principles are considered when presenting the recommendation in the user interface & no & yes & ERS do not take advantage of the semantic descriptions provided by educational standards and specifications. In SERS, this is a distinctive feature. \\ \hline F8. When recommendations are shown to the user, their description is also provided & no & yes & The recommendation information that can be shown by ERS is more limited than that shown by SERS. So, usability and accessibility issues are crucial in SERS, as recommendation related information needs to be displayed. \\ \hline \end{tabular}
\end{table} 
Table 2: Comparison between ERS and SERS. their description by the educator and the recommender logic when delivering recommendations in the running course. * **An open standards-based service-oriented architecture**, which serves to support the interoperability of the SERS with existing LMS through web services (F5). To this, SERS can take advantage of standards and specifications to describe the information exchange (F6). Further, it is advisable that SERS become a service integrated into the e-learning platform. * **A graphical user interface** to deliver the recommendations to the learners in a usable and accessible way (F7). This graphical user interface is to be developed within the corresponding LMS presentation layer and allows describing the recommendation and its features as informed by the recommendation model (F8). The above three elements are essential to properly support a semantically oriented recommendation process in education, which covers the management of recommendations by the educator [33] and complements the current functionality of LMS.