inform((_:search,type,'Train'))
user
I am looking for a train .
request((_:search,departure,?);(_:search,destination,?);(_:search,type,'Train'))
system
Alright , where will you be leaving from , or where are you heading ?
inform((_:search,departure,'stansted airport');(_:search,destination,'cambridge');(_:search,type,'Train'))
user
The train should go to cambridge and should depart from stansted airport .
inform((_:result,amount,'many options');(_:result,type,'Train')) request((_:search,arrive_by,?);(_:search,day,?);(_:search,leave_at,?);(_:search,type,'Train'))
system
Alright , I have many options for you depending on the day of the week or times you wish to travel . Do you have a preference ?
inform((_:search,day,'sunday');(_:search,people,'one');(_:search,type,'Train')) request((_:result,ref,?);(_:result,type,'Train'))
user
leaves at 1900hrs , arrives on sunday and booked fir one person.get me the reference number too
inform((_:booking,category,'Train');(_:booking,ref,'70MPLUW8');(_:booking,ticket,'10.1 GBP');(_:booking,type,'Booking'))
system
Booking was successful , the total fee is 10.1 GBP payable at the station . 
 Reference number is : 70MPLUW8 .
thank()
user
Thank you for your help .
system
Thank you goodbye
_:search type Train
_:search departure stansted airport
_:search destination cambridge
_:search type Train
_:search departure stansted airport
_:search destination cambridge
_:result amount many options
_:result type Train
_:search arrive_by ?
_:search leave_at ?
_:search day sunday
_:search people one
_:search type Train
_:result ref ?
_:search departure stansted airport
_:search destination cambridge
_:result amount many options
_:result type Train
_:search arrive_by ?
_:search leave_at ?
_:search day sunday
_:search people one
_:search type Train
_:result ref ?
_:booking category Train
_:booking ref 70MPLUW8
_:booking ticket 10.1 GBP
_:booking type Booking