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what in achieving them. Process-oriented approaches, on the other hand, specify
specific courses of action that are often violated by the actual actions undertaken
by relevant agents. Commitments specify interaction at a high level of abstraction.
They signify social relationships between agents and can be inferred solely from
the observable communication between agents. Moreover, compliance for an agent
simply means satisfying the commitments he has toward others
[34]
. We elaborate
on commitments in the following.
2.2 The Concept of Commitment
A commitment is of the form
C
(
debtor
,
creditor
,
antecedent
,
consequent
),
where
debtor
and
creditor
are agents, and
antecedent
and
consequent
are propo-
sitions. A commitment
C
(
x
,
y
,
r
,
u
) means that
x
is committed to
y
that if
r
holds, then
it will bring about
u
.If
r
holds, then
C
(
x
,
y
,
r
,
u
)is
detached
, and the commitment
C
(
x
,
y
,
T
,
u
) holds (
T
being the constant for truth). If
u
holds, then the commit-
ment is
discharged
and doesn't hold any longer. All commitments are
conditional
;
an unconditional commitment is merely a special case where the antecedent equals
T
. Examples 3-5 illustrate these concepts. In the examples, EBook is a bookseller,
and Alice is a customer; let
BNW
and $12 refer to the propositions
Brave New World
has been delivered
and
payment of
$
12 has been made
, respectively.
Example 3.
(Commitment)
C
(EBook, Alice, $12, BNW) means that EBook com-
mits to Alice that if she pays $12, then EBook will send her the book
Brave New
Wor l d
.
Example 4.
(Detach) If Alice makes the payment, that is, if $12 holds, then
C
(EBook, Alice, $12, BNW) is detached. In other words,
C
(EBook, Alice, $12,
BNW)
C
(EBook, Alice,
T
,BNW).
Example 5.
(Discharge) If EBook sends the topic (if
BNW
holds), then both
C
(EBook, Alice, $12, BNW) and
C
(EBook, Alice,
T
, BNW) are discharged. That
is to say, BNW
∧
⇒
$12
⇒
¬
C
(EBook, Alice,
T
,BNW)
∧
¬
C
(EBook, Alice, $12, BNW).
Importantly, an agent can manipulate commitments by performing certain oper-
ations (technically, speech acts). The commitment operations are reproduced below
Delegate
and
Assign
are three-party operations.
•
Create
(
x
,
y
,
r
,
u
) is performed by
x
, and it causes
C
(
x
,
y
,
r
,
u
) to hold.
•
Cancel
(
x
,
y
,
r
,
u
) is performed by
x
, and it causes
C
(
x
,
y
,
r
,
u
) to not hold.
•
Release
(
x
,
y
,
r
,
u
) is performed by
y
, and it causes
C
(
x
,
y
,
r
,
u
) to not hold.
•
Delegate
(
x
,
y
,
z
,
r
,
u
) is performed by
x
, and it causes
C
(
z
,
y
,
r
,
u
) to hold.
•
Assign
(
x
,
y
,
z
,
r
,
u
) is performed by
y
, and it causes
C
(
x
,
z
,
r
,
u
) to hold.
We introduce
Declare
(
x
,
y
,
r
) as an operation performed by
x
to inform
y
that
r
holds. This is not a commitment operation, but may indirectly affect commitments
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