Consider the following relation schema $($the primary keys are underlined$).$

Webpage $($webID$,$ webTitle, url, base, hits$)$

HttpLink $($sourceWebID$,$ targetWegID$)$

Graphic$($gID$,$ gName, gType, gLocation$)$

Display$($webID$,$ gID$)$

Courseware$($cID$,$ cDescription, ftpLocation, category$)$

ftpLink$($webID$,$ cID$)$

Write the following queries with relation algebra

For relation algebra solutions, you can copy and paste the following symbols as you need or use words such as selection, projection, rename, join, union, intersection, difference instead.

$\backslash$sigma $\backslash$pi $\backslash$rho $-$

Which webpages $($webTitle$)$ display 'gif' or $\text{'}$jpg$\text{'}$ graphics $($gif and jpgare gType $)?$

Which webpages $($find webID$)$ have more than $1000$ hits?

Which webpages $($find webTitle$)$ does not have ftplinks?

Which webpages $($find webID and webTitle$)$ display graphics?

Which webpages $($find webID$)$ use $$jpg$$ graphics, but not $$gif$$ graphics?