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# Consider the following schema representing a list of students: (a) Briefly answer the following questions: • What is the type of the attribute “names”? • What is the type of the attribute “ids”? •...

Consider the following schema representing a list of students:
(a) Briefly answer the following questions:
• What is the type of the attribute “names”?
• What is the type of the attribute “ids”?
• What is the type of the attribute “list”?
(b) Consider the following partially written schema that intends adding a new student to the list (the predicate part is not written yet). The schema should add a student to the student list and report success if the student is not in the list. If the student is already in the list then the list does not change and the result is set to already_exists.
You are required to complete the following tasks:
• Explain the meaning of Δ at the beginning of ΔStudentList.
• Explain, why the attributes “id?” and “name?” have question marks at the end?
• Explain, why the attribute “result!” has the exclamation sign at the end?
• Write the predicate part of AddStudent schema.
[ XXXXXXXXXX1 + 4 = 10 Marks]
[
Note: You can use the required notations from the following set of Notations:
Δ ,? , !, ∈, ∉ ,  ′ , ∪ , ∧, ↦ , ",  \$
]
Answered Same Day Jun 17, 2021

## Solution

Harsimran answered on Jun 17 2021
Consider the following schema representing a list of students:
(a) Briefly answer the following questions:
• What is the type of the attribute “names”?
Ans - It's a set containing names (ran list means range of function)
• What is the type of the attribute “ids”?
Ans - It's a set of strictly positive numbers that is linked to student's names.
(dom list means domain of function)
• What is the type of the attribute “list”?
Ans- It defines a partial function defining id is associated with student name
(b)...
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