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Topic: cotpi 41 - Counting locally prime numbers
Replies: 32   Last Post: Feb 29, 2012 2:17 AM

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 Mike Terry Posts: 639 Registered: 12/6/04
Re: cotpi 41 - Counting locally prime numbers
Posted: Feb 27, 2012 2:07 PM

"Tonico" <Tonicopm@yahoo.com> wrote in message
> On Feb 27, 8:50 am, cotpi <puzz...@cotpi.com> wrote:
...
> >
> > Let A be a set of 10 consecutive integers. Let B be a subset of A such
> > that every element in A that is coprime to every other element in A is
> > present in B. What are the possible values for the cardinality of B?
> >
> > I hope this helps.
> >
> > cotpi

>
>
>
> Take the set A:= {10, 11,..., 19} . As with any other of the given
> characteristics, it has exactly 5 even numbers and 5 odd numbers, and
> according to the presented condition NONE of the even numbers can be
> present in the wanted subset B (as any of these ones is NOT coprime
> with any other even element in A).

No, you're misreading (or I am...)

For A:= {10, 11,..., 19} we can have B:= A. (In fact, we can do this for
any A.)

Mike.

Date Subject Author
2/26/12 cotpi
2/26/12 Willem-Jan Monsuwe
2/26/12 Luis A. Rodriguez
2/26/12 Willem-Jan Monsuwe
2/26/12 quasi
2/26/12 Willem-Jan Monsuwe
2/26/12 quasi
2/26/12 Prai Jei
2/26/12 cotpi
2/28/12 Tim Little
2/26/12 Mike Terry
2/26/12 Mike Terry
2/26/12 Mike Terry
2/26/12 cotpi
2/26/12 Mike Terry
2/27/12 cotpi
2/27/12 J. Antonio Perez M.
2/27/12 Willem-Jan Monsuwe
2/27/12 Ted Schuerzinger
2/28/12 Willem-Jan Monsuwe
2/28/12 Ted Schuerzinger
2/27/12 Mike Terry
2/27/12 Mike Terry
2/27/12 Willem-Jan Monsuwe
2/27/12 Mike Terry
2/27/12 J. Antonio Perez M.
2/28/12 Willem-Jan Monsuwe
2/28/12 Mike Terry
2/28/12 J. Antonio Perez M.
2/27/12 Mike Terry
2/27/12 cotpi
2/26/12 cotpi
2/29/12 Tim Little