# Understanding Horizon 2020 Data: A Knowledge Graph-Based Approach
## 3 The Proposed Approach
### Graph Data Analysis and Visualization  
This section demonstrates features related to the analysis and visualization of our graph data through the following three representative queries:  
* _Q1: What are the topics of interest for each of the top-n organizations that have coordinated (or participated in) the most projects of H2020?_
* _Q2: For a given list of topics, which deliverables were produced by the top-n organizations that have coordinated (or participated in) the most projects of H2020 were related to pilot applications?_
* _Q3: Which people have been working on a given list of topics? Have they been working on additional ones?_  
To answer such questions in the Neo4j graph database, we employ the _Cypher_ graph query language, due to its expressiveness and native support. The cypher queries that we implemented can be found in Appendix B. To visualize these queries, we can use the _Neo4j Browser tool_, due to its ease of use and nice visualization features; it is noted that the graph database can also be accessed programmatically, using a driver plugin from multiple programming languages ([[https://neo4j.com/developer/language-guides/](https://neo4j.com/developer/language-guides/)]([https://neo4j.com/developer/language-guides/](https://neo4j.com/developer/language-guides/)) (accessed on 27 November 2021)). For large queries that return thousands of nodes and edges, we have also implemented a custom visualization tool, building on top of the neovis.js (accessed on 27 November 2021) graph visualization library, which has been also included in our GitHub repository ([[https://github.com/NCODER/CORDISKG](https://github.com/NCODER/CORDISKG)]([https://github.com/NCODER/CORDISKG](https://github.com/NCODER/CORDISKG)) (accessed on 27 November 2021)). This tool bypasses common memory limitations imposed by the _Neo4j Browser tool_ and has been used in the instances shown in Figures 4-6. Figure 4: Visualization of a specific organization and some of its projects and respective keyphrases. Q1 is a common query raised when an organization is about to shape a project proposal and identify potential partners (especially, \"big players\") to collaborate with. It is noted that the results of a graph query can either be a subgraph of the original graph or a table of aggregated results formed from the matched graph path. Figure 4 illustrates an instance of the subgraph returned by queries of Q1 type, visually representing the topics that the top organization (i.e., the one that has coordinated or participated in the most projects) has been working on, together with the associated projects. It is noted that, due to the very large number of projects this organization has been working on, the graph of Figure 4 is just a small part of the one returned by Q1. Q2 attempts to reveal information about the type of deliverables that were produced by organizations, which have participated in projects elaborating a certain list of topics. Particularly, Q2 focuses on deliverables reporting on the implementation (or evaluation) of a project's pilot applications (use cases). Figure 5 illustrates an instance of the subgraph returned by queries of Q2 type, visually representing the projects that one of the top organizations has been working on, together with the associated deliverables. As shown, whenever the user hovers over a node, detailed information about its properties and values appears. As above, due to space limitations, only a small part of the graph returned by Q2 is shown in this instance. Figure 5: Visualization of a specific organization and some of its projects and respective deliverables. Finally, Q3 is also a frequently asked question during the preparation of a research proposal, raised when one wants to identify colleagues with particular skills and competences that cover the needs of a call. Figure 6 illustrates an instance of the subgraph returned by queries of Q3 type, visually representing the deliverables that a person has been working on, together with the associated projects and topics.