Exercise · ZW-RULE-OF-INFERENCE-010 · ★★★ Advanced
A conclusion can be true and yet the step invalid if...
Choose one option.
Show answer
- D. It does not follow from the premises by the rule used
Explanation
A true conclusion is not enough: if it does not follow from the premises by the rule used, the step is invalid.
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-004 In a formal proof it is not allowed to...
- 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...