State the English meaning of the following algebraic expressions. The meaning of

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State the English meaning of the following algebraic expressions.
The meaning of this operator is as follows: A and B must be lists of attribute in r. The schema of counter A/B(r) consists of all attributes in B plus one addition attribute, which represents the counted value. The contorts of counter an defined as follows: for each tuple, t pi g r. (the projection on B). take A/B(r) and count the number of tuples in the resulting relation (where stands the set of all tuples in r whose value on the attributes in B is t. Let us denote i number by c(t). Then the relation counter A/B(r) is defined as You should be able to recognize the above construction as a straightforward. adaptation of GROUP BY of SQL to the relational algebra. State the English meaning of the following algebraic expressions (some of tl queries arc likely to yield empty results in a typical university, but this is be the point):

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Dear, a. List all CrsCodes from Transcript references Semesters b. List all Semesters from Transcript references CrsCode c. List all CrsCode, StuID from Transcript references StudentId thru Student table d. List all CrsCode, Semesters, StuID from Transcript references StudentId thru Student table

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