July 2006 Volume 9 Number 3 - CiteSeerX

Solving this problem involved the following database development concepts: defining, constructing,
manipulating, protecting and sharing databases. In this example, three students (students I, J and K) were in a
group. Student K submitted his portfolio and students I and J assessed independently student K’s portfolio.
Students I, J and K were allowed to construct their own fuzzy membership functions for the same evaluation
concepts such as Completeness, Security and Flexibility to assess the portfolio. Following the workflow
presented in Fig. 3, the assessment process was divided into the following steps.
Defining the Fuzzy Constraints
The instructor first explained each evaluation concept to the students. Students I, J and K defined membership
functions for each evaluation concept. Each membership function was considered as a fuzzy constraint. After
assessing student K’s portfolio, students I, J and K illustrated their own fuzzy constraints (Figures 4(a)(b)(c)).
(a) Student I (b) Student J (c) Student K
Figure 4. Fuzzy constrains
Student I specified the assessments as Fuzzy constraints, namely Low Completeness, Median Security and
Median Flexibility. Student J defined Median Completeness, Low Security and Median Flexibility as fuzzy
constraints and student K defined High Completeness, High Security, and High Flexibility as fuzzy constraints.
Suppose students I, J and K adopted concession and trade-off strategies.
Using Fuzzy Constraints to negotiation
Agents I, J and K represent students I, J and K respectively. Negotiation in this example is a multi-issue
negotiation among agents I, J and K. Agreement is achieved when all participants agree. Agents I, J and K took
I
turns attempting to reach an agreement. Agent I proposed its assessments u 1 = ( 60,
70,
70)
related to
Completeness, Security and Flexibility at threshold 1 1 =
I
I
α (Fig. 4(a)). However, according to (1), ( 1 ) = 0
C u μ J
I and ( 1 ) = 0 u
I
μ , agents J and K did not accept u1 as an agreement. Subsequently, agent J proposed its offer
K
C
1 ( 70,
60,
70)
=
J
J
J
u at threshold α 1 = 1.
However, agents I and K also did not accept u1 as an agreement. Agent K
then proposed its offer 1 ( 90,
90,
85)
=
K
u at threshold 1 1 =
K
α . However, agents I and J still did not accept K
u as an
1
agreement.
Furthermore, assuming agent K adopted the fixed concession strategy and had no expected proposal at threshold
K
K
α 1 = 1,
agent K lowered its threshold to next threshold α 1 = 0.
9 and created a new set of feasible proposals as
K
K
K
v = 90,
90,
83),
v = ( 90,
88,
85),
v = ( 88,
90,
85)
2 a
( 2b
2c
According to (5), the similarity among these feasible proposals was computed by agent K as
K
Θ
K
K K
v , u'
) = 0.
361,
Θ ( v , u'
) = 0.
366,
Θ v , u'
) = 0.
374
K K
( 2 a
2b
( 2 c
21