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Re: Yes
Posted:
Feb 5, 2013 1:03 PM


On Feb 5, 6:34 pm, Bart Goddard <goddar...@netscape.net> wrote: > Dan <dan.ms.ch...@gmail.com> wrote in news:43bcf4320c9a41e29eea > c91fe4e80...@ia3g2000vbb.googlegroups.com: > > > > > > > > > > > On Feb 5, 4:24 pm, Robin Chapman <R.J.Chap...@ex.ac.uk> wrote: > >> On 05/02/2013 14:08, Dan wrote: > > >> > On Feb 5, 3:45 pm, Robin Chapman <R.J.Chap...@ex.ac.uk> wrote: > >> >> On 05/02/2013 13:27, Dan wrote: > > >> >>> Does there always exist a subgroup H of G such that G = NH , and > >> >>> (H intersection N) = the identity element? > > >> > Can you provide an example? > > > Fun fact :If the set of possible answers is infinite , and person T (T > > stands for troll) claims to have one ,then person B cannot determine > > for sure using only yes or no questions . Each question is a function > > from the set of remaining answers to {Yes,No} . Provided that the set > > is infinite , either the inverse image to Yes or the inverse image of > > No is infinite . There exists a sequence of choices as answers of T > > such that the set of 'remaining valid answers' always remains > > infinite , thereby always giving the impression of knowledge of an > > answer , while ensuring for a fact that such an answer does not > > exist . > > That's an interesting alternative universe you've got there. Something > closer to reality would be that person T (T for teacher) doesn't want to > do your homework for you, but was helpful enough to tell you the right > answer, so that you wouldn't waste a lot of time looking for a proof > rather than a counterexample. I'm surprised you aren't more grateful. > > B.
'Z4' is two characters that would have been a sufficient answer .My fault , indeed , lies is not being able to see it. It's not a homework question , I simply thought of it while studying semidirect products. I will admit to stupidity , not malice , though I preferred it be the other way around , then I wouldn't be asking the question .



