$\backslash \{10$ points$\backslash \}$ Redundancy: what is it$?$ Why it is listed among the main advantages of the database approach? Explain.

$\backslash \{80$ points $\backslash \}$ Your task is to design a database for a small airline company storing information about AIRPORT$($s$),$ FLIGHT$($s$),$ and AIRPLANE$($s$).$ Consider ONLY the following points:

$($a$)$ Airplane$($s$)$ makes fight$($s$)$ from one airport $($the departure airport$)$ to another one $($the arrival airport$)\backslash (\{\}^\{1\}\backslash ).$ It is important to memorize the departure time and the arrival time.

$($b$)$ Every airplane in the database has at least the "total number seat" and the "model" attributes

$($c$)$ Each flight is identified by a unique $"$f number", and

$($d$)$ Every airport has at least a "name", and composite "address" $(5$ points$),$ and a multi$-$valued "telephone" attributes $(5$ points$)$

$($e$)$ Every flight offers SEATs

$($f$)$ Information about seats' reservation is kept for each fight: a "seat number" $(10$ points$)$ is unique only within one fight, and for every seat it is necessary to store its "price" and "state" $($free$,$ reserved, booked$)$

Questions:

$($i$)\backslash (\backslash \{5+5\backslash )$ points $\backslash (\backslash \}\backslash )$ Design the ER diagram and schema

$($ii$)\backslash (\backslash \{5+5\backslash )$ points $\backslash (\backslash \}\backslash )$ Which type of relationships do you have? Discuss both the cardinality and the participation constraints

$($iii$)\backslash \{10$ points $\backslash \}$ Give the corresponding relational schema of your database

$($iv$)\backslash (\backslash \{5\backslash )$ points $\backslash (\backslash \}\backslash )$ Give a possible snapshot of your database containing at least $5$ entries $($better if mean full $\backslash (\backslash \{5\backslash )$ points $\backslash (\backslash \})\backslash )$

$\backslash \{10$ points $\backslash (\backslash \}\backslash )$ Weak entity: what is it$?$ Can you give an example? $($refering to answer $2)$