please provide computer science answer

4. Consider three tables defined as follows: Author(author-id, name institution) Publication(pub-id,date,title) Writes(author-id, pub-id, order) These tables describe the operation of a database of publications. An author is identified by an author- id, which is numeric, and a publication is identified by its pub-id. The Writes table indicates which authors write which publications. The order field indicates the order of authors in the author list (i.e., 1,2,3,...). Attributes start with unique letters, so you can abbreviate your answers to the first letters in the following questions. Write relational algebra expressions to answer the following queries, or explain why such queries cannot be expressed in relational algebra.. If you assign names to the answers of queries using the arrow notation, you can re-use those names in later sub-parts. (a) Find the ids of authors who have never been first author in a publication. (b) Find the titles of publications with at least 10 authors. (c) Find the names of all authors who authored a publication that appeared on 1/20/2021. (d) Find pairs of distinct publication ids where the publications appeared on the same date and have an author in common. (Do not include both a pair and its reverse.) (e) Find the id of the author with name "Paul Erdos". (You can assume it's unique and in the database.) (f) Find the id of authors who have coauthored an article with Paul Erdos, but don't include Erdos himself. (These people have "Erdos number 1".) (8) Find the id of authors who have coauthored an article with somebody having Erdos number 1, but don't include Erdos himself or people with Erdos number 1. (These people have "Erdos number 2".) (h) Find the id of authors for which there is a chain of co-authorship (of any length, not some fixed length) linking them to Erdos. 4. Consider three tables defined as follows: Author(author-id, name institution) Publication(pub-id,date,title) Writes(author-id, pub-id, order) These tables describe the operation of a database of publications. An author is identified by an author- id, which is numeric, and a publication is identified by its pub-id. The Writes table indicates which authors write which publications. The order field indicates the order of authors in the author list (i.e., 1,2,3,...). Attributes start with unique letters, so you can abbreviate your answers to the first letters in the following questions. Write relational algebra expressions to answer the following queries, or explain why such queries cannot be expressed in relational algebra.. If you assign names to the answers of queries using the arrow notation, you can re-use those names in later sub-parts. (a) Find the ids of authors who have never been first author in a publication. (b) Find the titles of publications with at least 10 authors. (c) Find the names of all authors who authored a publication that appeared on 1/20/2021. (d) Find pairs of distinct publication ids where the publications appeared on the same date and have an author in common. (Do not include both a pair and its reverse.) (e) Find the id of the author with name "Paul Erdos". (You can assume it's unique and in the database.) (f) Find the id of authors who have coauthored an article with Paul Erdos, but don't include Erdos himself. (These people have "Erdos number 1".) (8) Find the id of authors who have coauthored an article with somebody having Erdos number 1, but don't include Erdos himself or people with Erdos number 1. (These people have "Erdos number 2".) (h) Find the id of authors for which there is a chain of co-authorship (of any length, not some fixed length) linking them to Erdos