# Databases - Relational Calculus

# Databases - Relational Calculus

ramey_steven + 0 comments Here is my stab at the logic, derived from giyam's answers below and Googling set notation:

**Give me the set of x such that for all y***in set(x) and set(y)*is a function of (where) y <= xHowever, I think the italicized section above is unclear due to the nature of the problem as it is written...that is, what is the relationship with y and 'S(x)' after ∀?

Definitions:

*∀ = forall*(https://en.wikipedia.org/wiki/Turned_A)*| = such that*(https://en.wikipedia.org/wiki/Set-builder_notation)*∧ = logical conjunction (and)*(https://en.wikipedia.org/wiki/List_of_logic_symbols)*→ = is a function from*(https://math.stackexchange.com/questions/1740154/different-arrows-in-set-theory-rightarrow-and-mapsto)

jackliusr + 0 comments find a specific x in set S which all numbers y in S are less or equal to x.

generalbaguette + 0 comments That's super weird notation. Why not use , also there should probably a colon or dot or space after the .

krsticsmederevac + 0 comments E moj faksu, neka korist i od tebe

shubham_mahawar + 1 comment Not understand the question properly It looks like find x from s(x) and y from s(y) and check y<=x

then there are many possible combination of this as 3<=3,4,5,6,7,10,11,19,18 4<=4,5,6,7,10,11,19,18 5<=5,6,7,10,11,19,18 6<=6,7,10,11,19,18 7<=7,10,11,19,18 10<=10,11,19,18 11<=11,19,18 18<=18,19 19<=19

total 45 but it is wrong anyone explain plz

matt_irby + 0 comments I'm going to take my stab at rephrasing the formula as it tripped me up to.

It's asking to find an x in S such that any y in S means y <= x.

So, it's asking which element in S is greater than or equal to any other element in S, including itself? This would be 19 because it is the greatest element in the set, therefore it is greater than or equal to all the other elements in the set.

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