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#1 2010-07-20 08:59:22

samuel12
Member
Registered: 2010-07-17
Posts: 19

logic

I'm having a few troubles with 'validly deduce'

Here is the question:

Q: For any set S of sentences, if T is a tautology, then you can validly deduce T from S.

Can anyone explain to me what it is to 'validly deduce' something, pretty confused here, cheers smile

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#2 2010-07-20 15:17:05

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: logic

T is a tautology, so it's always true. Therefore, you can always deduce it no matter what facts you start with.

For example, this is a valid deduction:

"If it rains tomorrow, then 3 is less than 7."


Why did the vector cross the road?
It wanted to be normal.

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