Exercise · ZW-FORMAL-PROOF-005 · ★☆☆ Basic
Which step does not belong to a formal proof?
Choose one option.
Show answer
- D. Asserting a conclusion without justification
Explanation
Every assertion must be justified, and asserting a conclusion without justification breaks formality. The other three options are valid steps.
Review the concept: Formal proof
A formal proof of \(\varphi_n\) is a sequence \(\varphi_1,\ldots,\varphi_n\) in which each term is an axiom, an admitted hypothesis, or the result of a rule applied to earlier terms.
\[\varphi_1,\varphi_2,\ldots,\varphi_n\vdash\varphi_n\]
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