BCNF Decomposition & FD Closure Demo
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To use, run the command "irb -r relation.rb" (requires ruby).
This will open an interactive ruby prompt.
To run unit tests, run the command "rspec *_spec.rb" (requires ruby and rspec).
To run the web frontend, run the command "ruby -r rubygems web_server.rb"
(this requires ruby, rubygems, mongrel, JSON, and CGI).
The web server will be started on http://localhost:3000.
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Determining the Closure of a Set of Functional Dependencies:
see functional_dependency_set_spec.rb for more info
1) Create a FunctionalDependencySet. The constructor takes a hash
representing the functional dependencies with the keys being
determinants and the values being dependants. Both are represented
as an array of strings.
>> s = FunctionalDependencySet.new({
?> ['A'] => ['B'],
?> ['B'] => ['C'],
?> ['B', 'C'] => ['D']
>> })
returns
=> #<FunctionalDependencySet ...>
2) Call the closure method.
>> c = s.closure
returns
=> #<FunctionalDependencySet ...>
3) Print the result.
>> puts c
outputs
A -> B, C, D ; B -> C, D
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Determining the BCNF Decomposition of a Relation:
see relation_spec.rb for more info
1) Create a Relation. The constructor takes an array of attributes and
a hash representing the functional dependencies.
>> r = Relation.new(['A', 'B', 'C'], {['A'] => ['B']})
returns
=> #<Relation ...>
2) Call the bcnf_decomposition method.
>> d = r.bcnf_decomposition
returns
=> [#<Relation ...>, ...]
3) Print the result.
>> puts d
outputs
(A, B), A -> B
(A, C)