School of Software Engineering, USTC (Suzhou)
Exam Paper for Academic Year 2019-2020-2
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Course: Formal Methods Time: July 14, 2020
Student Name: Student No.
Class: Score:
I: Propositional Logic
Given the following inference rules for propositional logic:
(V ar)
Γ, P ` P
(T 1)
Γ ` T
Γ ` ⊥
(⊥E)
Γ ` P
Γ ` P Γ ` Q
(∧I)
Γ ` P ∧ Q
Γ ` P ∧ Q
(∧E1)
Γ ` P
Γ ` P ∧ Q
(∧E2)
Γ ` Q
Γ ` P
(∨I1)
Γ ` P ∨ Q
Γ ` Q
(∨I2)
Γ ` P ∨ Q
Γ, P ` Q
(→ I)
Γ ` P → Q
Γ ` P → Q Γ ` P
(→ E)
Γ ` Q
Γ, P ` ⊥
(¬I)
Γ ` ¬P
Γ ` P Γ ` ¬P
(→ E)
Γ ` ⊥
Γ ` P ∨ Q Γ, P ` R Γ, Q ` R
(∨E)
Γ ` R
Γ ` ¬¬P
(¬¬E)
Γ ` P
1. (5 points) Draw the proof tree for proposition:
(P ∨ Q) → (Q ∨ P )
using the above inference rules.
II: Constructive Logic
2. (5 points) Given the following exclusive middle law (EM):
` P ∨ ¬P
Does this rule hold in constructive logic? Explain your conclusion. (Only write down your idea, no need to
write down strict proof.)
1