GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 65

Answer 1

First we compute the X-projection of $r$. Then we cross product with $s$, so,
$$
\left (\pi_X \;^{(r) \times s}\right).
$$
Will give us tuples $(\mathrm{X}, \mathrm{Y})$ where every value of $\mathrm{r} . \mathrm{X}$ is related to every value of $s.Y.$

Now we subtract actual tuples of $r$.

So, we will get those tuples $(\mathrm{X}, \mathrm{Y})$ which are NOT present in $r$. Now, we project $X$, So, we get those values of $r.X$ which are not related to some value of $s.Y.$

Answer 2

First cross product of ( projection X of r) and s means every r,x related to every s,y

 

then minus Original R

 

So , r.x are subtracted in which r.x related to every y

 

and those are not related to every y are left 

So , Answer should be Values of r.x which are not related to every value of s.Y

not in option

Comments

@Aaveg537, Your analysis is correct, but conclusion is not. Option $C$ correctly describes your analysis.

“Values of r.X which are not related to every value of s.Y” is ambiguous as it could mean the values of r.X which are not related to any value of s.Y.

Read & Consider option $C$: “Values of r.X which are not related to some value of s.Y”. It is what we want. 

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thank you sir !!!!