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Table 25.8 Linguistic descriptions for “normal” diseases Bronchitis / Pneumonia
Bronchitis Pneumonia
wheezing sometimes occasionally
breathlessness very seldom
often
anosmia
seldom
seldom
f ever
sometimes
often
sinusitis
sometimes
sometimes
chronic otitis
seldom
seldom
Table 25.9 Corresponding numerical descriptions for “normal” diseases Bronchitis and Pneu-
monia (Table 25.8)
d 1 d 2
s 1 0.4 0.6
s 2 0.2 0.75
s 3 0.25 0.25
s 4 0.4 0.75
s 5 0.4 0.4
s 6 0.25 0.25
that, to define such case, we need a crisp information. It is a clear situation, but is
not always a case.
The difficulty to suspect the RD is because of its symptomatic similarity to the
“normal cases”. Therefore, another alarm can be represented by possible diagnoses.
If a physician has enough experience with a computer program, s/he usually has
been working, and s/he mentions that the values for possible diagnoses are much
below or much above the usual representation, it can be also the sign of alarm “a
rare disease” for a physician.
We need to define appropriate operations and thresholds (that allow to detect
a deviation from the “normal” case). If we take max-min composition of fuzzy
relations (25.6), it restricts the maximum membership degree of possible diseases
for a patient by values in Table 25.9. For example, if a patient at hand has
S p = { (
s 1 ,
0
.
4
) , (
s 2 ,
0
.
2
) , (
s 3 ,
0
.
25
) , (
s 4 ,
0
.
4
) , (
s 5 ,
0
.
4
) , (
s 6 ,
0
.
25
) }
(25.9)
the possible diagnosis d 1 has the membership degree 0
.
4 (see (25.11)). If a patient
at hand has
S p = { (
s 1 ,
1
.
0
) , (
s 2 ,
1
.
0
) , (
s 3 ,
0
.
2
) , (
s 4 ,
0
.
25
) , (
s 5 ,
0
.
2
) , (
s 6 ,
0
.
2
) }
(25.10)
the possible diagnosis d 1 has the membership degree 0
.
4 as well.
 
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