[Official] Assignment 8

Disclaimer: Dieser Thread wurde aus dem alten Forum importiert. Daher werden eventuell nicht alle Formatierungen richtig angezeigt. Der ursprüngliche Thread beginnt im zweiten Post dieses Threads.

[Official] Assignment 8


I can’t seem to find it either. assignment7.pdf is still there, and assignments.pdf hasn’t been changed since the 18th.

1 Like

Hm still nothing there. I hope we will get an extended deadline once the assignment actually gets posted.

Still not online
Assignment 8 is still not online. When will it be? Are there plans for extending the deadline?

1 Like

Sorry, my push didn’t go through, and I didn’t check the forum over the weekend. It’s online now.

I have extended the deadline correspondingly.

Has_parent relation

we have a question regarding Problem 8.3 (cousin, nephew, niece). How is it possible to specify a “going up in the family tree” concept? e.g. specify a child that has a mother? We used the other relations to specify every other concept but struggle to get from cousin → mother → sibling → child.
Many thanks in advance.


Also to 8.3:
Can we use the concepts we already defined along the way for the other following concept definitions or are we constricted only to use the primitive concepts woman, man ?

1 Like

I got the feeling that this is simply not possible in ALC. We need some kind of has_parent role. So maybe, it was expected from us to say “this is not possible using these concepts and roles”?

What’s the difference (in 8.3) between has_child and hasdescendant? Is it that a persons stepchild is this persons child but it’s not its descendant? Another idea would be that a descendant can also be a grandchild, but then has_child and hasdescendant would be true for the exact same set of persons.


As there is nothing in the slides about flipping/turning a relation, I googled a bit and found this: https://lat.inf.tu-dresden.de/teaching/ws2013-2014/DL/handout2.pdf

On page 18 of the pdf it says that there is something called “inverse role” written with R^{-1}.

But I have no idea if this is official ALC and if it is allowed in the assignment. But in my opinion some of the concepts in 8.3 cannot be defined without that.

Could anybody give us some official answers, please?

Should the hasdescandant relation actually be the has_ancestor/has_parent relation?
Or should we use a of inverse relation there?


Sorry, I had a copy-paste error in the question - hasdescendant was meant to be has_parent.

I’ve uploaded a corrected version.

1 Like

Solutions posted

( ͡° ͜ʖ ͡°)


Oops, I misremembered the deadline extension that I put in studon and accidentally posted the solution early.

It would be unfair to remove them since some students have already downloaded them now. So I guess I’ll have to keep them online.

We’ll still grade as usual, and it’s still plagiarism if you copy the solutions verbatim.