Exercise · ZW-RULE-OF-INFERENCE-004 · ★☆☆ Basic
In a formal proof it is not allowed to...
Choose one option.
Show answer
- B. Use a step that is not justified
Explanation
A step without justification is not valid in a formal proof, so it is not allowed.
Review the concept: Rule of inference
A rule of inference authorizes the formal step from the premises \(\varphi_1,\ldots,\varphi_n\) to the conclusion \(\psi\).
\[\frac{\varphi_1,\ldots,\varphi_n}{\psi}\]
More practice problems: rule of inference
- ZW-RULE-OF-INFERENCE-001 A rule of inference indicates...
- ZW-RULE-OF-INFERENCE-002 A rule of inference normally relates...
- ZW-RULE-OF-INFERENCE-003 A conclusion in a formal proof must be accompanied by...
- ZW-RULE-OF-INFERENCE-005 Rules of inference help separate...
- ZW-RULE-OF-INFERENCE-006 A valid rule of inference preserves...
- ZW-RULE-OF-INFERENCE-007 A rule of inference typically has...
- ZW-RULE-OF-INFERENCE-008 Applying a rule without its premises holding is...
- ZW-RULE-OF-INFERENCE-009 Which of these options is a valid rule of inference that obtains ψ from φ → ψ and φ?