inform((_:search,departure,'london liverpool street');(_:search,destination,'cambridge');(_:search,type,'Train'))
user
I need a train from   london liverpool street to cambridge .
request((_:search,day,?);(_:search,leave_at,?);(_:search,type,'Train')) inform((_:result,amount,'many');(_:result,type,'Train'))
system
There are many trains . What day and what time ?
inform((_:search,day,'friday');(_:search,leave_at,'21:45');(_:search,type,'Train'))
user
I would like to leave on Friday after 21:45 please .
inform((_:result,id,'TR6769');(_:result,type,'Train')) offer((_:booking,category,'Train');(_:booking,type,'Booking'))
system
Train TR6769 fits what you 're looking for . Would you like me to book you passage ?
request((_:result,duration,?);(_:result,type,'Train'))
user
No , I just need to know the travel time of the train at the moment .
system
I will book it for you , is there anything else I can do for you ?
_:search departure london liverpool street
_:search destination cambridge
_:search type Train
_:search departure london liverpool street
_:search destination cambridge
_:result amount many
_:result type Train
_:search day friday
_:search leave_at 21:45
_:search type Train
_:search departure london liverpool street
_:search destination cambridge
_:result amount many
_:search day friday
_:search leave_at 21:45
_:search type Train
_:result id TR6769
_:result type Train
_:system offered _:booking
_:booking category Train
_:booking type Booking
_:result duration ?