Write the following queries in relational algebra, tuple relational calculus, and domain relational calculus. Note that some of these queries may not be expressible in relational algebra (and, therefore, also not expressible in tuple and domain relational calculus)! For such queries, informally explain why they cannot be expressed. (See the exercises at the end of Chapter 5 for additional queries over the airline schenla.) 1. Finel the eids of pilots certified for some Boeing aircraft. 2. Find the names of pilots certified for some Boeing aircraft.

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