Q1: Consider the Bellow schema for a library database and write relational algebra expressions for the following queries

1-Author ( authorname, citizenship, birthyear)

2-Book(isbn, title, authorname)

3-Topic(isbn, subject)

4-Branch(libname, city)

5-Instock(isbn, libname, quantity)

1-Give all authors names born after 1940.

2-Give the names of libraries in Sydney.

3-Give the book name and cities where each book is held.

4-Give the title of each book on the topic of either alcohol or drugs.

5-Give the title and author of each book of which at least two copies are held in a branch located in Melbourne.