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Logic Tool

Practice writing proofs using the standard rules of logic in an environment that provides explanations of the logic rules and gives immediate feedback on proofs.

In your assignments, logic questions will display with the Cengage Logic Tool. Use the Proof Builder within the tool to complete and check proofs.

  1. Open an assignment that uses the Cengage Logic Tool.
  2. Under Premise enter a line of your premise.
    If Premise comes pre-filled, move to the next step.
    1. Click open symbols pad to open and enter characters using the symbols pad.
      Common Logic Characters:
      Operator Name Logical Function Used to translate
      ~ tilde negation not, it is not the case that
      ⋅ dot conjunction and, also, moreover
      ∨ wedge disjunction or, unless
      ⊃ horseshoe implication if . . . then . . . , only if
      ≡ triple bar equivalence if and only if
    2. If needed, click add line to add one or more premises.
  3. Under Conclusion, click open symbols pad to enter a conclusion with the symbols pad.
    If Conclusion comes pre-filled, move to the next step.
  4. Enter your proof.
    1. Click Enter a line of proof > open symbols padto enter your proof.
    2. Click line # to enter numbers for your line of proof.
      Numbers must be entered in the format of a comma-separated list or a range of values.
      1,2 or 1-5.
      If line numbers are not needed to justify the proof, leave this box blank.
    3. Click Indent Line to indicate conditional or indirect proof sequences.
    4. Click Select a rule to enter a rule from the pad.
      Click expand under References to see a list of all the rules that can be input into your proof.
    5. Click check line to check if your line of proof is valid.

      If it's valid, a checkmark will show next to it. If invalid, a message titled Answer Feedback will appear and explain why.

      Note The validity of your line of proof will reset if any changes are made to the line.
    6. If needed, click add line to add additional lines of proof.
      Your previous line of proof must show as valid before you can add new lines.
    7. Click Delete line to delete a line of proof.
  5. Click Check Proof to check the validity of the complete proof and re-check all lines of proof.