What's that Language?

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Across
  1. 3. Contradiction
  2. 5. modustollens
  3. 6. conjunction
  4. 7. simplification
  5. 10. propositionalcaluculus
  6. 11. Identitylaws
  7. 12. implications
  8. 13. contrapositive
Down
  1. 1. Biconditional
  2. 2. inverse
  3. 4. Distributivelaws
  4. 8. Idempotentlaws
  5. 9. Commutativelaws