Assume, you are working with the following knowledge base:

family(person( john, cohen, date(17,may,1990), unemployed), person( lily, cohen, date(9,may,1990), unemployed), [ ] ).

family(person( john, armstrong, date(7,may,1988), unemployed), person( lily, armstrong, date(29,may,1961), unemployed), [ ] ).

family(person( eric, baily, date(7,may,1963), works( bbc, 2200)), person( grace, baily, date(9,may,1965), works( ntu, 1000)), [person( louie, baily, date(25,may,1983), unemployed) ] ).

family(person( eric, baily, date(7,may,1963), works( acc, 21200)), person( grace, baily, date(9,may,1965), works( ntnu, 12000)), [person( louie, baily, date(25,may,1983), unemployed) ] ).

family(person( eric, fox, date(27,may,1970), works( bbc, 25200)), person( grace, fox, date(9,may,1971), works( ntbu, 13000)), [person( louie, fox, date(5,may,1993), unemployed) ] ).

family(person( tom, cohen, date(7,may,1960), works( bcd, 15200)), person( ann, cohen, date(29,may,1961), unemployed), [person( pat, cohen, date(5,may,1983), works( bcd, 15200)), person( jim, cohen, date(5,may,1983), works( bcd, 15200)) ] ).

family(person( bob, armstrong, date(12,oct,1977), works( ntnu, 12000)), person( liz,armstrong, date(6,oct,1975), unemployed), [person( bob, armstrong, date(6,oct,1999), unemployed), person( sam,armstrong, date(8,oct,1998), unemployed) ] ).

family(person( tony, oliver, date(7,may,1960), works( bbc, 35200)), person( anny, oliver, date(9,may,1961), unemployed), [person( patty, oliver, date(8,may,1984), unemployed), person( jimey, oliver, date(5,may,1983), unemployed) ] ).

family(person( jack, fox, date(27,may,1940), unemployed), person( jane, fox, date(9,aug,1941), works( ntu, 13050)), [person( andy, fox, date(5,aug,1967), works( com, 12000)), person( kai, fox, date(5,jul,1969), unemployed) ] ).

husband(X) :- family( X, _, _).

wife(X) :- family( _, X, _).

child(X) :- family( _, _, Children), member(X, Children).

exists(Persons) :- husband( Persons); wife( Persons); child( Persons).

dateofbirth(person(_, _, Date, _), Date).

salary(person(_, _, _, works(_, S)), S).

salary(person(_, _, _, unemployed), 0).

Write the details of steps of search (unification, resolutions, and back tracking) and also the answer for each of the following queries. (You can show the details of your search process by drawing search trees for each of the following queries)

? exists(P), dateofbirth(P, date(_,_,Y)), Y<1963, salary(P, Salary), Salary<15000.

? exists(P), dateofbirth(P,date(_,_,Y)), !, Y<1998, salary(P,Salary), Salary<20000.

? wife(person(GivenName, FamilyName, _, works(_,_))).

? child(X), dateofbirth(X, date(_,_,1983)).

Consider the database from the previous question and answer the following

1) Write a prolog rule totalIncome/2 to compute the total income of a family.

2) Write a prolog query to print total income of each family.

3) Write a prolog query to print family details of each family that has income per family member less than 2000.

4) Write a prolog query to print family details of each family where childrens total income is more than their parents.