Transcript A Blackboard Globally Recast as an Interpreter

- Jairam Kamath
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A Blackboard Globally Recast as
an Interpreter
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A Blackboard Globally Recast as an Interpreter
• The solution space is organized into several applicationdependent hierarchies and the domain knowledge
partitioned into independent modules of knowledge that
operate on knowledge within and between levels.
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• The blackboard model of problem solving is a highly
structured special case of opportunistic problem solving.
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Three Major parts:
• Knowledge sources
• The blackboard data structure
• Control
Example: HEASRSAY – II
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Basic architecture of a blackboard system
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----> Control flow
____ Data flow
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----> Control flow
____ Data flow
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• HEARSAY-II speech recognition system.
• The blackboard structure is a six- to eight-level hierarchy in
which each level abstracts information on its adjacent lower
level.
• blackboard elements represent hypotheses about the
interpretation of an utterance.
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-Blackboard
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• Knowledge sources correspond to such tasks as segmenting
the raw signal, identifying phonemes, generating word
candidates, hypothesizing syntactic segments, and proposing
semantic interpretations.
• Each knowledge source is organized as a condition part that
specifies when it is applicable and an action part that
processes relevant blackboard elements and generates new
ones.
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-Knowledge Sources
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• The control component is realized as a blackboard monitor
and a scheduler.
• The scheduler monitors the blackboard and calculates
priorities for applying the knowledge sources to various
elements on the blackboard.
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-Control
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----> Control flow
____ Data flow
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• The complexity arises because it is now illustrating two
concepts: The blackboard model and realization of that model
by a virtual machine.
• The blackboard model can be recovered by suppressing the
control mechanism and regrouping the conditions and actions
into knowledge sources.
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Interpreter View
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• The interpretation engine includes several components like:
the blackboard monitor, the focus of control database, and the
scheduler, but also the actions of the knowledge sources.
• The scheduling queue corresponds roughly to the control
state.
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Interpreter View
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• We see a system initially designed with one model
(blackboard, a special form of repository), then realized
through a different model (interpreter).
• The view as an interpreter is a different aggregation of
components from the view as blackboard.
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Conclusion
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Thank You 
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