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A Rationale-based Model for Architecture Design Reasoning

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10.3. <strong>Reasoning</strong> about change impact with AREL<br />

Decision AR10 depends on four requirements (i.e. R2 3 1, R2 3 4, R2 3 5 and R4 1 3 ).<br />

From the conditional probability table (CPT), R4 1 3 is more influential to AR10 than<br />

the other three requirements because when it becomes volatile, the probability that AR10<br />

is valid drops to 0.2. (i.e. P (AR10 = V |R2 3 1 = S, R2 3 4 = S, R2 3 5 = S, R4 1 3 = V )<br />

= 0.2) The influence is due mainly to whether acknowledgement message should be processed<br />

asynchronously or not.<br />

(a)<br />

(b)<br />

Figure 10.5: A BBN Representation with prior probabilities/CPTs of a Payment Message<br />

<strong>Design</strong>: (a) Asynchronous Message Processing (b) Security<br />

AR14 depends on requirements R2 5 1, R2 5 2 and design C4 2 4. However, C4 2 4<br />

180

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