[Date Prev][Date Next]
[Chronological]
[Thread]
[Home]
Re: Philosophy general debate
To reply to this message or start a new topic please email: BUPS-DIS@bups.org
> Thanks for the responses to my 'lemma' question. From what I read, I was
> correct to suspect that I could use it in the context I suggested. When I
> asked a lecturer at uni 'is that a lemma?' (can't remember the example), I
> was simply told 'No.'.
>
Hmm, I doubt I gave a good enough explanation of what a lemma was then. I would
tend to agree with your lecturer here, when it's a three step proof then it
doesn't really count (otherwise everything would be a lemma, since P would be a
lemma for [P or Q] for any Q). I think its something you pick up from looking at
examples, e.g. typically in first year analysis courses you will get to prove
(if I remember correctly) that every bounded sequence of real numbers had a
convergent subsequence (Weierstrass Bolzano Theorem). To prove this we prove a
couple of 'lemmas' - helpful results which make the WB theorem easy to swallow.
Namely that every bounded monotone increasing sequence converges, and that every
bounded sequence has a monotone increasing subsequence. It is easy to see how we
get WB once we have these two lemmas.
I hope that's clearer.
--
Andrew Bacon
Lady Margaret Hall
07830048336
http://users.ox.ac.uk/~lady1900
Browse or search the BUPS-DIS archives, or unsubscribe from the mailing list at: http://www.bups.org/mailinglist.shtml