16) In distributed database systems, what are the responsibilities of a transaction coordinator? [2/40] 17) Briefly describe how RDF (Resource Description Framework) graph datasets and linked data can be queried. [2/40] 18) Briefly describe the concept of 'Eventual Consistency' in big data storage systems. [2/40] 19) What are the two categories of consensus algorithms used in public blockchain based storage systems? [2/40] 20) Suppose that an online company has stored millions of movie reviews in its database. After purchasing a reasonable amount of labeled review data, it wants to analyse if reviews in its database are positive or negative, e.g. for sentimental analysis. Propose two algorithms for this task. [2/40]