XpVista.pro prolog assignment

%check if a windows is xp.
isxp(xphome).
isxp(xpprofessional).
isxp(xpmediacenter).
isxp(xpmediacentre).
isxp(xptabletpc).

%checks if a windows is vista.
isvista(vistastarter).
isvista(vistahomebasic).
isvista(vistahomepremium).
isvista(vistabusiness).
isvista(vistaenterprise).
isvista(vistaultimate).

%check if a windows is 7
is7('7starter').
is7('7homepremium').
is7('7professional').
is7('7enterprise').
is7('7ultimate').

%xp to vista, where it requires two times upgrade
%twotimesupgrade(xphome,vistatovista(vistabusiness,vistaenterprise)).
%twotimesupgrade(xphome,vistatovista(vistahomebasic,vistahomepremium)).
%twotimesupgrade(xpprofessional,vistatovista(vistabusiness,vistaenterprise)).
%twotimesupgrade(xptabletpc,vistatovista(vistabusiness,vistaenterprise)).

%some xp needs to clean install (Format) in order to upgrade to vista.
needs_clean_install(xpprofessional,vistahomebasic).
needs_clean_install(xpprofessional,vistahomepremium).
needs_clean_install(xpmediacenter,vistabusiness).
needs_clean_install(xpmediacenter,vistahomebasic).
needs_clean_install(xptabletpc,vistahomebasic).
needs_clean_install(xptabletpc,vistahomepremium).

%upgrading among vista versions
vistatovista(vistabusiness,vistaenterprise).
vistatovista(vistahomebasic,vistahomepremium).

%vista to 7
%information available from
%http://arstechnica.com/microsoft/news/2009/02/upgrading-to-windows-7-what-xp-and-vista-users-need-to-know.ars
%[Accessed 21-Jan-2010]
%vistato7(vistahomepremium,7homepremium).
%vistato7(vistabusiness,7professional).
%vistato7(vistaultimate,7ultimate).

%windows 7 to windows 7
%http://windows.microsoft.com/en-us/windows7/products/windows-anytime-upgrade
%[Accessed 21-Jan-2010]
%w7to7('7starter', W7) :- is7(W7), W7 \= 7starter.

%all xp can upgrade to Vista, except those that requires Format.
upgrade(Xp, Vista) :- isxp(Xp), Vista \= vistastarter, not(clean_install(Xp,Vista)).
%upgrade(Vista, W7) :- vistato7(Vista,W7).
%upgrade(Vista1,Vista2) :- vistatovista(Vista1,Vista2).

%create synonyms for clean install
clean_install(X,Y) :- needs_clean_install(X,Y).
require_format(X,Y) :- needs_clean_install(X,Y).

%check if a windwos is vista, except ultimate version.
isnotultimate(V):- isvista(V), V \= vistaultimate.

%all vista can upgrade to ultimate directly, except vista ultimate itself.
toultimate(V) :- isnotultimate(V).
%all xp can direct upgrade to vista ultimate directly.
toultimate(Xp) :- isxp(Xp).