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GPSS assignment
# GPSS assignment

## General Information

- The due date is
**Friday 3**^{rd} December 2004, before
23:55.

- Submissions must be done via WebCT.
Beware that WebCT's clock may differ slightly from yours.
As described on the Assignments page,
*all* results
must be uploaded to WebCT and accessible from links in the
index.html file.

- The assignment can be made in groups of upto 2 people.
It is understood that all partners will understand the
complete assignment (and will be able to answer questions
about it).

- Grading will be done based on correctness and completeness
of the solution. Do not forget to document your
assumptions, model, simulation results, conclusions in detail !

- Extensions, if given, will involve extending not only the
alotted time, but also the assignment !

## The problem statement

Pierre, the owner of the famous restaurant "Chez Pierre" wants to
simulate the flow of customers through his restaurant. Based on the
simulation results, Pierre wants to, if necessary, make some changes to
his restaurant.
Empirical study taught Pierre that customers typically arrive in groups
of 1, 2, 3, or 4 customer with relative probabilities of 10%, 50%,
20% and 20%.
The distribution of interarrival times between subsequent groups is
exponential with an average of 5 minutes.
"Chez Pierre" currently has 12 small tables and at each table,
there is room for 2 customers. Tables can be joined to serve parties
of more than 2 customers.
When a group of hungry customers arrives, they have to wait until they
get the undivided attention of Pierre who will seat them, if tables are
available.
If 10 groups of customers are already queueing, a new arriving group
will find another restaurant.
Pierry is rather stingy and does not only receive incoming customers,
but also acts as cashier.
If no customers are waiting to be seated, Pierre will go to the cash
register. If customers are waiting to be seated, Pierre -who is
shortsighted- tries to seat the first group of waiting customers.
This, without taking into account the fact that this may block
other groups of customers. It is namely possible that though there is no
seating space for the first group of customers (as it is too large), one
of the other waiting groups could be seated.
In the exclusive restaurant Chez Pierre, it is out of the question
that more than one group would be put at the same table.
The time Pierre needs to re-arrange tables and seat a group of customers
is uniformly distributed between 1 and 3 minutes.
When a group is seated, Pierre goes to the cash register while
the group of customers waits uniformly distributed between 20 and 30
minutes to order and be served (taking customers' orders and serving
is done by waiters -not by Pierre- who are not explicitly modelled
here).
The time to eat is uniformly distributed over 1h+-15min.
After seating the group, Pierre will serve all customers waiting to
pay at the counter. This takes uniformly from 0.5 to 1 minute per group.
If there are no more waiting customers, Pierre looks for 15s
at the proceeds of the evening.
Then, he again waits for arriving customers.
## The assignment

- Model "Chez Pierre". The model needs to be submitted in textual form.
A graphical representation is optional.

- Simulate the flow of customers (and Pierre) in the restaurant
during an evening from 18h to 23h. One hour before closing time,
no more new customers are allowed in.

- Output must be generated which describes in detail statistics of:
- the number of served customers

- the number of customers leaving due to a too long queue

- the length of queues

- the time spent in the restaurant by customers

Results for the different simulation
runs corresponding to alternative modifications (see below)
of "Chez Pierre" must be submitted along with the models.

- Evaluate Pierre's efficiency and suggest and implement improvements.
You should at least experiment with different numbers of tables.

## Practical information

For simulation, use GPSS World, student edition which
is installed on the SOCS Windows server (use `rdesktop -f windows`.
You can download
GPSS
World student edition from
www.minutemansoftware.com.
The software has a builtin help. The online reference manual is at
www.minutemansoftware.com/reference/reference_manual.htm.
A note to Linux users: GPSS World can be installed under Linux using
the free implementation of Windows for Unix
wine by running
`wine -managed -winver win98 student.exe`. Your mileage may vary.

File translated from
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by
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version 3.40.

On 19 Nov 2004, 00:15.