Information Technology Reference
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Wilma could have succeeded according to PP4, but in fact Bert is rightly unpersuaded,
satisfying OP2.
Having made these distinctions we will now focus on a particular sub-type of per-
suasion dialogue, open persuasion involving preferences. This is the simplest kind of
dialogue after inquiry dialogues, in that only one side is doing the persuasion, and the
participants have common goals. Our particular scenario is the common situation where
an agent is seeking a recommendation, or comparing options, concerning things such
as restaurants, cars, digital cameras, insurance, or any other product where competing
options have some out of a large number of features that vary in importance for different
agents. The persuading agent will want what is best for the other agent, and will have
no particular interest in having its recommendation accepted. The particular topic we
will consider is
what is an acceptable restaurant for Bert
?
3
Example
For our example we will spell out choice of restaurant in detail. Let us suppose that
Wilma and Bert are standing outside Burger World. Bert can see that Burger World is
close by and appears cheap, but as a stranger to the town knows nothing about any other
restaurant. Wilma, on the other hand, as a native to the city, has complete information.
So, initially, Bert finds Burger World acceptable but Wilma will attempt to persuade
him of the merits of the Thai Palace. Moreover suppose Bert wants a good quality
restaurant that is cheap, close by and licenced. Bert weights these attributes 6,2,1 and 2
respectively. All other features of restaurants, such as whether they have music, and the
type of cuisine, are matters on which Bert is indifferent, and so have weights of 0, and
need not be considered. We can summarise the situation:
Set of Agents
AG
=
{
Wilma, Bert
}
. Wilma is the persuader and Bert is the persuadee.
Set of Options
O
=
{
BurgerWorld, ThaiPalace
}
=
{
O
1
,
O
2
}
Set of Attributes
A
O
=
{
goodQuality, cheap, close, licenced
}
=
{
a
1
,a
2
,a
3
,a
4
}
Sets of weights.
W
Wilma
(
a
i
)
=
{
}
;
W
Bert
(
a
i
)
=
{
}
6,4,0,2
6,2,1,2
;
for
i
= 1,2,3,4.
Truth values
τ
ij
. Burger world (
j
=1
)
{
0,1,1,0
}
(cheap and close). Thai Palace
(
j
=2)
{
1,1,0,1
}
: (good quality, cheap and licenced).
Each agent, for each option, partitions
A
O
into four subsets, depending on its own
knowledge base. Attributes that are not known and have not yet been the subject of an
inquiry are
unverified
, while those that have been the subject of an inquiry are
verified
,
and the agents are in agreement as to them. If an attribute cannot be shown true, it is
considered to be false since the defeasible reasoner uses negation as failure. So at the
start of the dialogue,
Bert has
UT
1
=
{
cheap, close
}
,UF
1
=
{
good, licenced
}
,VF
1
=
VT
1
=
∅
for
Burger World and
UF
2
=
∅
for the Thai Palace. As the dialogue progresses, inquiries regarding attributes are made,
and these attributes will move from unverified to verified. Bert's utility calculations for
Burger World at the start of the dialogue are shown in Figure 1.
{
good,cheap,close,licenced
}
,UT
2
=
VF
2
=
VT
2
=
