Consider the following proof of that IS supposed to prove the tautology: (A v B → C^ D) → (B → D) Proof: 1. AVВ — СлD P 2. ¬(B → D) P for IP 3. B^ ¬D 2 4. B 3, ?

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
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Consider the following proof that is supposed to prove the tautology:

\[
(A \lor B \to C \land D) \to (B \to D)
\]

**Proof:**

1. \( A \lor B \to C \land D \)  \hspace{2em} \( P \)
2. \( \neg(B \to D) \)  \hspace{2em} \( P \) for IP
3. \( B \land \neg D \)  \hspace{2em} 2
4. \( B \)  \hspace{2em} 3, ?
5. \( A \lor B \)  \hspace{2em} 4, ?
6. \( C \land D \)  \hspace{2em} 1, 5, ?
7. \( \neg D \)  \hspace{2em} 3, ?
8. \( D \)  \hspace{2em} 6, ?
9. \( D \land \neg D \)  \hspace{2em} 7, 8, ?
10. False  \hspace{2em} 9, Contr

**QED: 1, 2, 10, IP**

The above proof is correct. However, in lines 4 -- 9, we have not indicated the Proof Rule being used (indicated by a `?`). Which of the following choices gives the correct sequence of Proof Rules for these lines?

- ○ Add, Add, Conj, DN, Contr, Conj
- ○ Simp, Add, MP, Simp, Simp, Conj
- ● Simp, Simp, Add, Simp, DN, Contr
- ○ Add, Simp, Simp, Simp, Simp, Contr
Transcribed Image Text:Consider the following proof that is supposed to prove the tautology: \[ (A \lor B \to C \land D) \to (B \to D) \] **Proof:** 1. \( A \lor B \to C \land D \) \hspace{2em} \( P \) 2. \( \neg(B \to D) \) \hspace{2em} \( P \) for IP 3. \( B \land \neg D \) \hspace{2em} 2 4. \( B \) \hspace{2em} 3, ? 5. \( A \lor B \) \hspace{2em} 4, ? 6. \( C \land D \) \hspace{2em} 1, 5, ? 7. \( \neg D \) \hspace{2em} 3, ? 8. \( D \) \hspace{2em} 6, ? 9. \( D \land \neg D \) \hspace{2em} 7, 8, ? 10. False \hspace{2em} 9, Contr **QED: 1, 2, 10, IP** The above proof is correct. However, in lines 4 -- 9, we have not indicated the Proof Rule being used (indicated by a `?`). Which of the following choices gives the correct sequence of Proof Rules for these lines? - ○ Add, Add, Conj, DN, Contr, Conj - ○ Simp, Add, MP, Simp, Simp, Conj - ● Simp, Simp, Add, Simp, DN, Contr - ○ Add, Simp, Simp, Simp, Simp, Contr
Consider the following proof of the tautology:

\[
(A \rightarrow C) \rightarrow (A \land B \rightarrow C)
\]

Proof:

1. \( A \rightarrow C \)
2. \( A \land B \)
3. \( A \)
4. \( C \)
5. \( A \land B \rightarrow C \)

QED

This proof is an example of applying:

- [ ] Neither IP nor CP Rules
- [ ] Both CP and IP Rules
- [ ] IP Rule
- [x] CP Rule

### Explanation

The proof shows a logical deduction where the implication \( (A \rightarrow C) \rightarrow (A \land B \rightarrow C) \) is verified. It uses the assumption from line 2, \( A \land B \), and the given \( A \rightarrow C \) to arrive at the conclusion \( A \land B \rightarrow C \).

This uses the Conditional Proof (CP) Rule:

- The proof assumes \( A \land B \) to establish \( A \land B \rightarrow C \) using previous deductions.
Transcribed Image Text:Consider the following proof of the tautology: \[ (A \rightarrow C) \rightarrow (A \land B \rightarrow C) \] Proof: 1. \( A \rightarrow C \) 2. \( A \land B \) 3. \( A \) 4. \( C \) 5. \( A \land B \rightarrow C \) QED This proof is an example of applying: - [ ] Neither IP nor CP Rules - [ ] Both CP and IP Rules - [ ] IP Rule - [x] CP Rule ### Explanation The proof shows a logical deduction where the implication \( (A \rightarrow C) \rightarrow (A \land B \rightarrow C) \) is verified. It uses the assumption from line 2, \( A \land B \), and the given \( A \rightarrow C \) to arrive at the conclusion \( A \land B \rightarrow C \). This uses the Conditional Proof (CP) Rule: - The proof assumes \( A \land B \) to establish \( A \land B \rightarrow C \) using previous deductions.
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