Q1 [10 points]. Take the following specification of a TESTRESCUE, an alarm system that tests itself and
calls a rescue support team when a repeated error occurs. You can use the FPS reference guide at the end of
the exam sheets.
Q1a [4 points]. Draw a labelled transition system for the process TEST.
-
Q1 [2 points]. Draw a labelled transition system for the process RESCUE.
Q1c [4 points]. Draw a labelled transition system for the composite process TESTRESCUE.
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, Partial grades (most common cases):
- 3 points if correct synchronization but wrong starting point
Q2 [10 points]. Consider the table below that shows environmental and shared phenomena for a bank
vault and its control software.
Environmental phenomena Shared phenomena
E1: The vault door is open S1: doorLocked = false
E2: An authorized user is in the vault S2: doorClosedSensors = open
E3: The alarm is playing S4: authorizationGiven = true
E4: An unauthorized user is in the vault S3: alarmStatus = on
S5: movingObjectInVault = true
An engineer has defined the following two system requirements:
R1. If the vault door is open and an authorized user is in the vault, then the alarm shall not be playing
E1 E2 → E3
R2. The alarm shall be playing if and only if the vault door is open and there is no authorized user in the vault
E1 E2 E3
Q2a [3 points]. According to the system requirements, is it possible for a thief to enter the vault without
activating the alarm sound? Why (not)?
It is certainly possible, because the second system requirement should state E1 E4 → E3. However, the
iff condition is not sufficient: what if someone breaks in without opening the door? A better requirement
would be E4 E3, assuming that only authorized users can enter the vault at all times, even when the
vault is empty.
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calls a rescue support team when a repeated error occurs. You can use the FPS reference guide at the end of
the exam sheets.
Q1a [4 points]. Draw a labelled transition system for the process TEST.
-
Q1 [2 points]. Draw a labelled transition system for the process RESCUE.
Q1c [4 points]. Draw a labelled transition system for the composite process TESTRESCUE.
Page | 1
, Partial grades (most common cases):
- 3 points if correct synchronization but wrong starting point
Q2 [10 points]. Consider the table below that shows environmental and shared phenomena for a bank
vault and its control software.
Environmental phenomena Shared phenomena
E1: The vault door is open S1: doorLocked = false
E2: An authorized user is in the vault S2: doorClosedSensors = open
E3: The alarm is playing S4: authorizationGiven = true
E4: An unauthorized user is in the vault S3: alarmStatus = on
S5: movingObjectInVault = true
An engineer has defined the following two system requirements:
R1. If the vault door is open and an authorized user is in the vault, then the alarm shall not be playing
E1 E2 → E3
R2. The alarm shall be playing if and only if the vault door is open and there is no authorized user in the vault
E1 E2 E3
Q2a [3 points]. According to the system requirements, is it possible for a thief to enter the vault without
activating the alarm sound? Why (not)?
It is certainly possible, because the second system requirement should state E1 E4 → E3. However, the
iff condition is not sufficient: what if someone breaks in without opening the door? A better requirement
would be E4 E3, assuming that only authorized users can enter the vault at all times, even when the
vault is empty.
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