Difference between revisions of "Binary decision diagram"
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We now have a canonical reduced ordered binary decision diagram. All nodes now represents different functions that all are canonical. | We now have a canonical reduced ordered binary decision diagram. All nodes now represents different functions that all are canonical. | ||
| − | '''Problem:''' This procedure becomes impossible with | + | '''Problem:''' This procedure becomes impossible with many variables. |
| − | + | ||
'''Solution:''' Build the reduced tree directly from the boolean expression. | '''Solution:''' Build the reduced tree directly from the boolean expression. | ||
'''How:''' To be determined... | '''How:''' To be determined... | ||
| + | # Recursively walk the circuit gate by gate from the input to the output and perform each operation on the BDD tree. | ||
Latest revision as of 10:43, 8 May 2014
- Decide order of variables
- Create truth table
- Create tree from truth table
- Merge equivalent leaves - We want two leaves, [ 1 ] and [ 0 ]. Redirect all edges from the removed nodes to the equivalent leave
- Merge isomorphic nodes - Remove all nodes that have the same variable and identical children as another node. Redirect all edges that went into the redundant node into the one copy that you kept
- Eliminate redundant tests - Remove all nodes that has the same child twice. Redirect all edges into redundant node into the child node
- Repeat steps 4 5 6 until no more improvements can be made
We now have a canonical reduced ordered binary decision diagram. All nodes now represents different functions that all are canonical.
Problem: This procedure becomes impossible with many variables.
Solution: Build the reduced tree directly from the boolean expression.
How: To be determined...
- Recursively walk the circuit gate by gate from the input to the output and perform each operation on the BDD tree.
