课程名称︰逻辑
课程性质︰通识A4
课程教师︰傅皓政
开课学院:
开课系所︰
考试日期(年月日)︰2017/11/06
考试时限(分钟):90
试题 :
一、请建构命题逻辑语言(提示:包括符号与形构规则两个部分)。(10%)
(Construct a suitable language for propositional logic. Hint: two parts
involved, alphabets and formation rules)
二、请判断下列陈述的真假,并且分别以T与F代表“真”与“假”。(10%)
(Please judge the following statements which are true or false. Notice,
please use the symbols "T" and "F" which stand for true and false
statements respectively.)
_ 1. 结论是矛盾句的论证可能是有效论证。
_ 2. 前提出现矛盾句的论证一定是有效论证。
_ 3. 前提与结论一致的论证可能是有效论证。
_ 4. 前提实际上为假而且结论实际上为真的论证一定是有效论证。
_ 5. 前提不可能全部为真的论证可能是无效论证。
_ 6. 有效论证中至少必须有一个前提实际上为真。
_ 7. 前提实际上为真而且结论实际上为假的论证可能是有效论证。
_ 8. 前提与结论都是偶真句的论证可能是有效论证。
_ 9. 前提与结论不一致的论证一定是有效论证。
_ 10. 前提与结论实际上为假的论证一定是无效论证。
三、请判断下列句式哪些是恒真句、矛盾句或者是偶真句。你可以使用任何学过的方法,
包括真值表法、简易真值表法或真值树法,必须列出演算过程。(15%)
(Using some method (e.g. truth table, short-cut or tableaux system) shows
that each of the following formulae is tautology, contradiction, or
indeterminate formula. Computational process is required.)
(a) D → ((C Λ D) → D)
(b) ┐(H → G) Λ ┐(G → H)
(c) (K → (L → M)) → ((K → L) Λ (K → M))
四、请判断下列各题中的两个句式之间是蕴涵或是等值关系。如果是蕴涵关系,以φ╞ψ
表示;若为等值关系,则以╞φ←→ψ表示,必须列出演算过程。(15%)
(Using some methods determine the semantic relation between the following
formulae. If the entailment relation holds then show them of the form
φ╞ψ. On the other hand, show them of the form ╞φ←→ψ if they are
equivalent. Computational process is required.)
(a) M V (N → N) ; M V N
(b) (P Λ Q) V (Q Λ R) ; (┐P Λ ┐Q) V (┐Q Λ ┐R)
(c) ┐(┐A Λ ┐B) ; ┐B → A
五、请写出等值于真值表中语句φ的DNF及CNF。(10%)
(Find out the DNF and CNF each which is equivalent to the following
formulae φ.)
(a) (b)
┌─┬─┬─┬─┐ ┌─┬─┬─┬─┐
│L│M│N│φ│ │G│H│K│φ│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│T│T│T│T│ │T│T│T│T│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│T│T│F│F│ │T│T│F│T│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│T│F│T│T│ │T│F│T│F│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│T│F│F│F│ │T│F│F│T│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│F│T│T│F│ │F│T│T│F│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│F│T│F│T│ │F│T│F│F│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│F│F│T│T│ │F│F│T│T│
├─┼─┼─┼─┤ ├─┼─┼─┼─┤
│F│F│F│F│ │F│F│F│T│
└─┴─┴─┴─┘ └─┴─┴─┴─┘
六、请以真值树法证明下列语法序列是否为有效论证,若为无效论证请显示其反例结构。
(20%)
(Please use tableaux system to prove whether each of the following
argument is valid. And specify a counterexample if it is invalid.)
(a) (Q V ┐P) → ┐R ; (P Λ Q) → R ├ (Q Λ R) → ┐P
(b) K → L ; K V (L ←→ K) ├ ┐K
七、请完成下列演算,作答时须连同题目写在答案卷上。(10%)
(Please complete the following proofs. Notice: you should copy the whole
questions on your answer sheet.)
(a) 证明 ├ ┐A → (A → B)
(1) (┐B → ┐A) → (A → B) _______________
(2) ((┐B → ┐A) → (A → B)) →
(┐A → ((┐B → ┐A) → (A → B))) _______________
(3) ┐A → ((┐B → ┐A) → (A → B)) _______________
(4) (┐A → ((┐B → ┐A) → (A → B))) →
((┐A → (┐B → ┐A)) → (┐A → (A → B))) _______________
(5) (┐A → (┐B → ┐A)) → (┐A → (A → B)) _______________
(6) ┐A → (┐B → ┐A) _______________
(7) ┐A → (A → B) _______________
(b) 证明 ┐┐K ├ K
(1) ┐┐K _______________
(2) ┐┐K → (┐┐┐┐K → ┐┐K) _______________
(3) ┐┐┐┐K → ┐┐K _______________
(4) (┐┐┐┐K → ┐┐K) → (┐K → ┐┐┐K) _______________
(5) ┐K → ┐┐┐K _______________
(6) (┐K → ┐┐┐K) → (┐┐K → K) _______________
(7) ┐┐K → K _______________
(8) K _______________
八、古典逻辑的语意学有三个默认,其中的真值函映原则设定古典逻辑的运算符号都必须
是真值函映的运算符号,然而实际上有很多运算符号是非真值函映的运算符号,请举
一个实例说明非真值函映的运算符号。(10%)
(There are three important postulates of the semantics of the classic
logic, one of them is the so-called the principle of truth-functionality.
Nonetheless we have many non-truth functional operators in our ordinary
language. Please take an non-truth functional operator to illustrate.)
Appendix: Rules of inference
命题逻辑公理系统(propositional logic axiomatic system)
公理(axioms):
(A1) φ → (ψ → φ)
(A2) (φ → (ψ → θ)) → ((φ → ψ) → (φ → θ))
(A3) (┐φ → ┐ψ) → (ψ → φ)
推论规则(rule of inference):
(MP) 从 φ 和(φ → ψ)成立,可以推论出 ψ 成立。