Consider the database consisting of the following tables Team(team id, name, city) Player(player id, name, playing_position, address) Picked(team id, player id, contract_duration_in_months) In case you cannot type the usual RA Greek letters easily, you should use the following convention. Operator parameters should be enclosed in square brackets. Selection Union UU os TT Intersection | X Difference D Projection Cross- product Join Conditional Join J Rename PR NO CJ T title (pointe-6 (courses)) can be written as P[title](S[points=6](courses)) Write down the Relation Algebra (RA) expressions for the following queries: a) Find out the name of the players who has not been picked for any teams yet. b) Find the name of the players who has a contract duration of less than 6 months with the Barcelona team