Solution - Exercises INF3110
		      week 44 31.10. - 4.11.2011


Exercise 1
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Remember that constants are written in lowercase and variables start always with uppercase letters.

1. studies(ivar, informatics).  
2. population(norway, 4.5). 
3. rich_country(norway). 
4. prime(2).  
5. author(hamlet, someone). 
6. mortal(X):- humans(X). 
7. pays_taxes(X):- person(X), rich(X). 
8. takes(ivar, umbrella):- raining. 

9. 
   man(X)  :- fbEmp(X) . 
   tallerTh6Ft(X) :- fbEmp(X) .
   tallerTh6Ft(X) :- height(X,Y) , moreTh(Y,6) . 




Exercise 2
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biography(X,Y,2003).


Exercise 3
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indian(curry). 
indian(tandoori). 
indian(tikkaMasala). 

mild(tandoori). 
hot(curry). 
hot(tikkaMasala). 

italian(pizza). 
italian(spaghetti).

likes(ola,Food) :- indian(Food), mild(Food). 
likes(ola,Food) :- italian(Food). 


Exercise 4 
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likes(Person,Food) :- indian(Food), mild(Food), nationality(nor,Person). 
likes(Person,Food) :- italian(Food), nationality(nor,Person). 
%likes(Person,Food) :- indian(Food), (hot(Food); mild(Food)), nationality(ind,Person). 
likes(Person,Food) :- indian(Food), nationality(ind,Person). 

nationality(nor,ola)
nationality(ind,samir)


Exercise 5 
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star(sun). 
star(sirius). 
star(vega). 

orbits(mercury, sun). 
orbits(venus, sun).
orbits(earth, sun). 
orbits(mars, sun). 
orbits(moon, earth). 
orbits(deimos, mars). 

planet(B):- orbits(B, sun). 

satellite(B):- orbits(B,P), planet(P). 

solar(sun). 
solar(B):- planet(B); satellite(B).


Exercise 6 
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1. tel(hundre_meter_skogen, ole_brumm, N). 
2. tel(C,P,123). 
3. local(N1,N2):- tel(C,P1,N1),tel(C,P2,N2), N1 \== N2 .
4. notOK :- tel(C1,P1,N),tel(C2,P2,N), C1\==C2. 
   notOK :- tel(C1,P1,N),tel(C2,P2,N), P1\==P2.

4. To get a listing of which numbers are not OK, define the rules: 
sameNo(C1,P1,C2,P2,N) :- tel(C1,P1,N),tel(C2,P2,N), C1\==C2. 
sameNo(C1,P1,C2,P2,N) :- tel(C1,P1,N),tel(C2,P2,N), P1\==P2. 

and use the query: 
sameNo(C1,P1,C2,P2,N) .

Exercise 7 
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a) 
connection(X,Y):- reindeerLine(X,Y). 
connection(X,Y):- reindeerLine(X,Z),connection(Z,Y). 

b) 
For example: 
Question: reindeerLine(northpole,X), reindeerLine(X,moscow). 
Answer: X  = stockholm



Exercise 8
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natural_number(0).
natural_number(s(X)) :- natural_number(X).

a)

plus(0,X,X) :- natural_number(X).
plus(s(X),Y,s(Z)) :- plus(X,Y,Z).

Note: It would be also possible to write only "plus(0,X,X)." in the first part of the definition.

b)

mult(0,X,0) :- natural_number(0).
mult(s(X),Y,Z) :- mult(X,Y,XY), plus(XY,Y,Z).

Note: It would be also possible to write only "mult(0,X,0)." in the first part of the definition.