Knowledge Representation Problem (John F. Sowa)
Date: Wed, 28 Sep 94 05:59:58 -0400
From: (John F. Sowa)
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Subject: Knowledge Representation Problem
Precedence: bulk
At the recent ANSI X3T2 meeting in Seattle, the following example was
suggested as a test case for modeling in conceptual schema languages.
The goal is to represent the relevant information in the problem in
a form that (a) captures all the significant information in a precise
form and (b) organizes the information in a way that can be used to
design the databases and programs necessary to implement a reservation
system for these hotels.  The representation should capture both the
static information about the entities and relationships and the dynamic
information about their interactions.  It should represent all the
relevant constraints and conditions on transactions and interactions.

This example is typical of the kind of information that must be
represented for business problems.  Some of the participants will
also try to put together an engineering/design problem.  There is
no shortage of candidate problems, but it is difficult to find
something that can be described in a page or two and still be
representative of the kinds of problems that arise in real life.

John Sowa
This example describes a prototype reservation system for the National
Park Service.  It is being designed for the Old Faithful Inn Hotel
in the Yellowstone National Park, the El Tovar Hotel in the Grand Canyon
National Park, and the Ahwahnee Hotel in Yosemite National Park.  The
hotels can be uniquely identified by their names.  The hotels have a
normal address (line 1, line 2, city, state, zip code) and each one has
a telephone number and a fax number.  Each hotel has a rating from
Mobile Travel Service of a certain number of diamonds (from one to
five).  Hotels may only be open for a certain period of a year.  They
may also have seasonal rates that reflect the change in demand for their
rooms.  Room rates are constant for different types of rooms during a
season.  Reservations are accepted for up to 13 months in advance (i.e.,
in January of 1994 reservations can be made through January of 1995).
Reservations cannot be made in a hotel before it is open for business
nor after it is scheduled for permanent closure.

Rooms in the hotel are of different types and are for either smoking or
non-smoking rooms.  Reservations select a room type and a smoking
category.  If a room is changed to a different type or smoking category,
the change is effective on a certain date.

Individual reservations can be made by an individual or a travel agent.
Reservations are confirmed for a specific time period and specific room
types and smoking categories.  An individual will give his/her name,
address (see example above), phone and po ssibly a fax.  A travel agent
also gives this information plus the agent's name and the travel agency
identification number.  This number will identify the specific travel
agency making the reservation, its address, its telephone, and its fax
number.  Each reservation is made by a reservation clerk and is
identified by a sequential number.  When a reservation is complete,
a time-stamp is made for audit purposes.

If a reservation cannot be confirmed, the reservation clerk will ask if
the guest would like to be wait-listed.  The wait-list is for either a
specific hotel or a category of hotels (number of diamonds) at a
national park.  The wait-list is for a certain period of days from the
reservation date.  If room(s) matching the request on the reservation
become available within the wait-list time period a confirmation is
automatically sent.  On the day before the wait-list is to expire,
the guest is contacted and asked if the wait-list should be extended
or if the room type(s) and smoking category(ies) could be changed
to allow a reservation to be confirmed.

When a reservation is made, it must be for either 16.00 hr arrival or be
guaranteed.  A 16.00 hr arrival time allows a reservation to be made and
at 16.00 hr on the date of arrival the reservation is automatically
canceled without a penalty being assessed to the guest.  To hold a
reservation after 16.00 hr the guest must guarantee the room.  The
guarantee is implemented through a credit card.  A guest tells which
type of credit card is to be used to guarantee the room and he/she must
provide the credit card number and an expiration date.  If a guest with
a guaranteed reservation does not show up and does not notify the hotel
that he/she will not arrive then the first night's rent for each
reserved room will be charged against the credit card.  Guests are
encouraged to cancel their reservation if their travel plans change so
that others on the wait-list can be accommodated.  Guaranteed rooms can
be canceled until 16.00 hr on the date of arrival and receive a
cancellation number that insures that the guest will not be charged for
the room.  If a guaranteed reservation is canceled after 16.00 hr on the
date of arrival then the hotel attempts to rent the room(s).  If the
room(s) are rented (this is decided based on the time of the
cancellation and does not take into account the type or smoking category
of the room), then a message is sent to the guest stating that he/she
has not been charged for the room.  If the room(s) are not rented, then
the hotel management decides whether or not the guest will be charged
and thus receive a notice that he/she has been charged or not charged
and thus be notified of this.

A confirmation is sent to the guest when it occurs.  Each confirmation
is time stamped for audit purposes when it occurs.  The confirmation
includes all information pertinent to the reservation.

The cancellation notice is sent to the guest if a cancellation number is
issued.  The notice identifies the reservation and the clerk that
canceled the reservation.  A time stamp validates that the reservation
was canceled in time to avoid a penalty.

Check-in occurs upon the arrival of the guest at the hotel.  The time of
check-in is noted and the departure date is confirmed.  Room number(s)
are assigned and keys are given to the guests.  If a credit card is to
be used for payment, then the informatio n previously noted is
collected.  A guest may use a different credit card for the stay than
the one used to guarantee the reservation.  The Park Service also has a
policy that hotel bills above a certain limit must be cleared before the
guest is allowed t o remain in the hotel.  The check-in process notifies
the guest of the limit that he/she must abide by.  Because of the
flexible reservation policy, walk-in guests without reservations are
encouraged - especially right after 16.00 hr.

At the time of check-in a guest may designate one room as the primary
room and other identified room(s) would have their charges appear
directly on the primary room's invoice.  This allows a family to have
only one bill even though they are occupying seve ral rooms.  Invoices
show which room made each charge so that guests can better audit their
own bills.  Guests who have regularly paid their bills when they reached
their account balance limits normally check out on their departure date.
All guests in ro oms that charge a primary room must check-out when the
guests in the primary room check-out.  The check-out time is used to
prevent any further charges from being invoiced to a room.  At check-out
a guest is given a copy of the invoice showing all charges and how the
balance was cleared.  If a guest does not make a payment when his/her
account balance reaches the predetermined limit the guest is
automatically checked-out.  Extensions to stays are routinely made if
rooms are available.