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Syllogism

Check if individual statements are well-formed formulas and if whole arguments are valid in in Aristotelian logic.

Installation

Add this line to your application's Gemfile:

gem 'syllogism'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install syllogism

Usage

# Individual statements:
Syllogism::Statement.parse('all 1s are numbers').tap do |invalid_statement|
  invalid_statement.wff? # => false
  invalid_statement.errors
  # => ["'1s' is an unknown atom", "'numbers' is an unknown atom"]
end

Syllogism::Statement.parse('all X is Y').tap do |valid_statement|
  valid_statement.wff? # => true
  valid_statement.errors # => []
end

# Entire arguments:
Syllogism['all P is S', 'j is P', 'j is S'].valid? # => true
Syllogism['no A is B', 'no C is A', 'no C is B'].valid? # => false

# Arguments with the same logical form are considered equivalent:
argument = Syllogism["all A is B", "some C is A", "some C is B"]
other_argument = Syllogism["all X is Y", "some Z is X", "some Z is Y"]

argument == other_argument # => true

# Generate random argument
Syllogism.sample.statements.map(&:to_s)
=> ["all M is C", "no L is M", "some L is C"]

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/jaysonvirissimo/syllogism.

License

The gem is available as open source under the terms of the MIT License.

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Proof checker for arguments in Aristotle's term logic

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