MathDB
Problems
Contests
International Contests
Danube Competition in Mathematics
2007 Danube Mathematical Competition
1
1
Part of
2007 Danube Mathematical Competition
Problems
(1)
Danube Mathematical Competition 2007 Problem 1
Source: a bit similar to IMO 2007 Pr. 1
12/8/2007
Let
n
≥
2
n\ge2
n
≥
2
be a positive integer and denote by
S
n
S_n
S
n
the set of all permutations of the set
{
1
,
2
,
…
,
n
}
\{1,2,\ldots,n\}
{
1
,
2
,
…
,
n
}
. For
σ
∈
S
n
\sigma\in S_n
σ
∈
S
n
define
l
(
σ
)
l(\sigma)
l
(
σ
)
to be \displaystyle\min_{1\le i\le n\minus{}1}\left|\sigma(i\plus{}1)\minus{}\sigma(i)\right|. Determine
max
σ
∈
S
n
l
(
σ
)
\displaystyle\max_{\sigma\in S_n}l(\sigma)
σ
∈
S
n
max
l
(
σ
)
.
algebra proposed
algebra