states - Behavior Modeling Class models express properties...

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Behavior Modeling • Class models express properties that are true of a system at all times • Although they are general, they fail to convey interesting behavioral aspects of systems – That is, how objects respond to external stimuli • A variety of alternative modeling techniques are available in UML for behavior modeling – Use case diagrams, sequence diagrams, statechart diagrams, activity diagrams, timing diagrams, interaction overview diagrams, communications/collaboration diagrams
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Modeling Alternatives • Combinatorial Control – Decision tables – Decision trees • Sequential Control – State transition tables – Finite state machine • Concurrent Control – State charts – Petri Nets – Activity diagrams – Sequence diagrams – Collaboration diagrams – Temporal logic – Process algebra
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Combinatorial Modeling • The simplest form of behavior modeling merely expresses the logic of simple combinatorial systems • In these systems, only the inputs, and not the history of previous states determines subsequent states • Two equivalent forms of combinatorial modeling are decision tables and decision trees
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Decision Tables One common way to model control is with decision tables. They are used when a number of possible input conditions hold and a number of responses are possible The conditions are called inputs and the responses are called outputs The input side of the table enumerates all possible combinations of conditions. For example, if each of three switches can have one of two possible values, "on" or "off", then the table will contain three columns and eight rows Likewise, if the three switches control two output devices (one switch is a master override) then there will be two output columns (along with the eight rows from the input). 3
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Example Decision Table - 1 OFF OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF ON OFF OFF OFF ON ON OFF OFF OFF OFF OFF ON ON OFF ON OFF ON OFF ON OFF ON ON ON ON ON ON ON Motor Lights Power Switch Light Switch Master Control Output INPUT
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Condensed Decision Table • Note that the last four rows of the output are identical. The table can be shortened by making use of "don't care" entries. A don't care entry is indicated by dashes in an input cell OFF OFF --- --- OFF OFF OFF OFF OFF ON ON OFF ON OFF ON OFF ON OFF ON ON ON ON ON ON ON Motor Light Power Switch Light Switch Master Control Output INPUT
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Decision Trees • A decision tree contains the same information as a decision table, but in graphical form • There are two kinds of nodes – Diamonds denote decisions – Rectangles denote actions to be taken • Labeled arcs indicate the implications when a decision is answered in a particular way (affirmative or negative) • Note that some nodes may be duplicated
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Decision Tree Master Controller On?
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This note was uploaded on 04/11/2010 for the course CS- 6505 taught by Professor Venkat during the Spring '09 term at Georgia Institute of Technology.

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states - Behavior Modeling Class models express properties...

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