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sasa...@msn.com

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Nov 23, 2017, 11:08:46 AM11/23/17
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Hi guys :) I am totally new to prolog and therefor could use some help with a homework. I already asked the question on stackoverflow, but for what I really needed, the guy stopped responding and the homework is due to tomorrow :/ 

So we need to formulate these sentences into Prolog: 

-Bill owns a dog. 

-Every dogowner likes animals. 

-Every person who likes animals cannot hit an animal. 

-Bill or Bull hit a cat whose name is Tom. 

-Every cat is an animal.

owns(bill,dog). 

likes(X,animals):- owns(X,dog).

cannothit(X,animal):- likes(X,animals). or hit(X,animal):- \+ likes(X,animal)

With the 4th sentence I have a major problem because I do not know how to state that or. 


It would be so awesome if someone could help me. 


 

Barb Knox

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Nov 23, 2017, 10:35:42 PM11/23/17
to swi-p...@googlegroups.com, sasa...@msn.com
On 24/11/2017, at 05:08, sasa...@msn.com wrote:

Hi guys :) I am totally new to prolog and therefor could use some help with a homework. I already asked the question on stackoverflow, but for what I really needed, the guy stopped responding

and the homework is due to tomorrow :/ 

(Oops!)


So we need to formulate these sentences into Prolog: 

1.  Bill owns a dog. 

2.  Every dogowner likes animals. 

3.  Every person who likes animals cannot hit an animal. 

4.  Bill or Bull hit a cat whose name is Tom. 

5.  Every cat is an animal.

owns(bill,dog). 

Not quite.  Bill owns *a* dog, i.e. some (unknown to us) thing which is a dog.

I would code it as:
owns(bill, Pet), dog(Pet).

likes(X,animals):- owns(X,dog).

Again, I’d use Pet with dog(Pet) instead of dog.
Further, does X like *some* animals or *all* animals (including, e.g., large venomous spiders)?  It makes a difference.
As it stands, you are saying X likes some *particular* thing with the name “animals”.  Not good.  You can finesse the issue by using a predicate animal_lover(X).

cannothit(X,animal):- likes(X,animals). or hit(X,animal):- \+ likes(X,animal)

Definitely use hit as your predicate, rather than cannothit.  You will need hit for sentence 4.

Also, as with Pet, use hit(Hitter, Hittee) with animal(Hittee).

With the 4th sentence I have a major problem because I do not know how to state that or. 

That is indeed a problem.  Look up “disjunction” in your text.


It would be so awesome if someone could help me. 

I hope this is of some help.  You are unlikely to get correct homework in on time, but hopefully you’ve learned a couple of useful things.


IMO and FWIW, this is a *poor* problem for beginners.  Your instructor(s) may be less than adequately competent with Prolog.  They would not be the first….


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|  BBB                b    \    Barbara at LivingHistory stop co stop uk
|  B  B   aa     rrr  b     |
|  BBB   a  a   r     bbb   |   ,008015L080180,022036,029037
|  B  B  a  a   r     b  b  |   ,047045,L014114L4.
|  BBB    aa a  r     bbb   |
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