關於logical thinking 既問題(急)8

2009-04-26 10:45 pm

Translate the following arguments into symbolic form. Then determine whether each is valid or invalid by constructing a truth table for each.

1. Brazil has a huge foreign debt. Therefore, either Brazil or Argentina has a huge foreign debt.

2. If fossil fuel combustion continues at its present rate, then a greenhouse effect will occur. If a greenhouse effect occurs, then world temperatures will rise. Therefore, if fossil fuel combustion continues at its present rate, then world temperatures will rise.

可否解釋一下?? 我真的不懂....

回答 (1)

myisland8132

2009-04-27 2:41 am

✔ 最佳答案

1 Let p: Brazil has a huge foreign debt q:Argentina has a huge foreign debt.
The symbolic form is
p => p v q
The proposition is valid
2 Let p:fossil fuel combustion continues at its present rate
q: a greenhouse effect will occur
r: world temperatures will rise
The symbolic form is
(p=>q) ^ (q=>r) => (p=>r)

The proposition is also valid

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