First, the proposition is symbolized, and the individual domain is the total individual domain. commemorate

p(x):x

It's a zebra; q(x):x

Striped; A: Mark.

Premise: ax (p (x) → q (x)); p(a)；

Conclusion: q(a)

Prove:

①

Ax(p(x)→q(x))

Introduction of preconditions

②

p(a)→q(a)

①

User interface rules

③

technical term

Introduction of preconditions

④

Ask (answer)

② ③ Hypothetical reasoning

Therefore, it is proved that.

2.

First, propositions are symbolized and recorded.

P: the earth is flat; Q: You can drive to the edge of the earth;

Premise: p→q, ┐q

Conclusion: ┐ P;

Prove:

①

p→q

Introduction of preconditions

②

┐p∨q

① replacement

③

┐q

Introduction of preconditions

④

┐p

②

③ disjunctive syllogism

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Note: All the above statements are from Qu Wanling's Discrete Mathematics.