Processing math: 100%

Identifier
Values
[1] => [1,0] => 10 => 01 => 1
[2] => [1,0,1,0] => 1010 => 0101 => 1
[1,1] => [1,1,0,0] => 1100 => 0011 => 1
[3] => [1,0,1,0,1,0] => 101010 => 010101 => 1
[2,1] => [1,0,1,1,0,0] => 101100 => 001101 => 3
[1,1,1] => [1,1,0,1,0,0] => 110100 => 001011 => 1
[2,2] => [1,1,1,0,0,0] => 111000 => 000111 => 1
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Description
The number of minimal chains with small intervals between a binary word and the top element.
A valley in a binary word is a subsequence 01, or a trailing 0. A peak is a subsequence 10 or a trailing 1. Let P be the lattice on binary words of length n, where the covering elements of a word are obtained by replacing a valley with a peak. An interval [w1,w2] in P is small if w2 is obtained from w1 by replacing some valleys with peaks.
This statistic counts the number of chains w=w1<<wd=11 to the top element of minimal length.
For example, there are two such chains for the word 0110:
0110<1011<1101<1110<1111
and
0110<1010<1101<1110<1111.
Map
to binary word
Description
Return the Dyck word as binary word.
Map
parallelogram polyomino
Description
Return the Dyck path corresponding to the partition interpreted as a parallogram polyomino.
The Ferrers diagram of an integer partition can be interpreted as a parallogram polyomino, such that each part corresponds to a column.
This map returns the corresponding Dyck path.
Map
reverse
Description
Return the reversal of a binary word.