relational

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Add theta-join binary operator

3

In our course, we use the theta-join (θ-join) operator: https://en.wikipedia.org/wiki/Relational_algebra#%CE%B8-join_and_equijoin

terencode

ltworf

``` empty = πroom(σ id is None (people ⧓ person_room ⧓ rooms)) full = πroom(σ r==room and i != id ( πr,i (ρ room➡r, id➡i ( people ⧓ person_room ⧓...

ltworf

`σ date is None or date.month== 8 (people*dates⧓skills)` It doesn't get picked up because of accessing `date.month` rather than just `date`.

ltworf