Download - LSE Research Online

initials(
hear(Welcome. I am going to try and help you put on your artificial leg.
The first step is to get all the bits you need))
literals(strings,
yes,no)
property(Can_ Finish,
possible(
hear(Well done! You have now put your leg on safely)))
property(Finish_ Or_ Help,
inevitable(
or(
hear(Well done! You have now put your leg on safely),
hear(Ask a person if you need some help))))
property(Remove_ Footplates,
possible(
Sequence(
deny(Have you removed the footplates that might be in the way?),
agree(Would you like some help?),
hear(Slide your hand down the side of the chair until you find a raised clip),
agree(Have you found a raised clip?),
hear(Put your thumb inside the clip and pull it out),
agree(If you have two footplates, remember to remove both.
So, have you now taken both footplates out of the way?))))
Figure 7: Sample Verification Properties for Limb Donning
ing will be automated in a future version of the approach.) The test scenarios
and verification properties reflected what the dialogues were expected to say, not
what the C RESS diagrams actually said. As a result, a number of failures were
encountered and corrected, arising from small editorial inconsistencies.
As an example, ‘Can you put the liner on?’ vs. ‘Can you put on the liner?’ are
equivalent but unnecessary variations in a dialogue that might confuse people
with cognitive impairment. The original dialogues were also found to use pronouns frequently, e.g. ‘Is it too tight?’ rather than ‘Is the liner too tight?’. Since
the dialogues are taken slowly in practice, someone with cognitive impairment
could easily miss the referent. The scenarios and properties were formulated as
consistent and unambiguous statements of what the dialogues should do. It was
only when these were checked against the C RESS descriptions that differences
were found.
Dialogue Links The dialogues have frequent links to connectors elsewhere in their diagrams. For the largest dialogue (Smoothie), it was found that in some cases the
C RESS diagram branched to the wrong place (reflecting an error in the original
G UIDE description). Fortunately this dialogue was not a safety-critical one (and
23