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Consider the relation employee(name, sex, supervisorName) with name as the key, supervisorName gives the name of the supervisor of the employee under consideration. What does the following Tuple Relational Calculus query produce?

$\left\{e.name \mid employee(e) \wedge \left(\forall x\right)\left[\neg employee\left(x \right) \vee x.supervisorName \neq e.name \vee x.sex = ``male" \right]\right\}$

  1. Names of employees with a male supervisor.
  2. Names of employees with no immediate male subordinates.
  3. Names of employees with no immediate female subordinates.
  4. Names of employees with a female supervisor.

6 Answers

1 votes
1 votes
here we need to use quantifiers inter conversiom,

 

i.e. if we use the for all conversion to ' not there exist' and thus in process invert all boolean varables within braces then we get the desired result as option (c)
Answer:

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