... second coordinate (i.e., the number of ways of
“placing k non-taking rooks on B”). It has long been known [5] that the rook numbers
of a board B determine the rook numbers of the complementary board ... subset of [d] × [d](where[d]isdefinedtobe{1, 2, ,d})andtherook
numbers r
B
k
of a board are the number of subsets of B of size k such that no two elements
have...
... A short proof
The following theorem first appeared in [3, Theorem 31, pp. 447–457]. (Actually, this
is not quite true. The theorem there was claimed only for uncountable orders into
which neither ... [X]
4
exists.
In the light of Theorems 2 and 3, a positive resolution of the following question
would be the best improvement of Theorem 1 possible.
Question 1. If X is an orde...
... 1)-factor of G avoiding e, then G − E(F
2k+1
) is a (2m − (2k + 1))-
factor containing e, and the proof is complete.
Corollary 2 (Kano and Yu [1] 2005) Let G be a connected r-regular graph of even
order. ... edge e of G, G has a 1-factor containing e, then G has a k-factor
containing e and another k-factor avoiding e for all integers k with 1 ≤ k ≤ r − 1.
The following example wil...
... exactly once.
In this paper, we give a short proof for the result of Noonan [3] that the number
of permutations of length n containing exactly one occurence of pattern 321 is
3
n
2n
n−3
.
(To ... A short proof for the number of permutations
containing pattern 321 exactly once
Alexander Burstein
Department of Mathematics
Howard University
Washington, ... Aug 23, 2...
... extension of the Littlewood-Richardson rule [Z].
Taking the specialization λ =
, we obtain the decomposition of s
µ/ν
into Schur
functions; it is simpler than the traditional formulation of the Littlewood-Richardson
rule ... b
i
free k + 1’s in
row i of T , then there should be b
i
free k’s and a
i
free k + 1’s in row i of σ
k
(T ).
In the following, T
≥j
denotes the s...
... number of boxes in the first row is equal to the
size of the first part, the number of boxes in the second row is equal to the size of the
second part, etc. For example, the Ferrers diagram for the ... that the set S consists of pairs of partitions with no primed parts. In the
definition of φ
−1
when there is a primed integer in the image, we consider only...
... of the hive give λ
• the differences on the Northeast side of the hive give µ
• the differences on the South side of the hive give ν
where all differences are computed left-to-right throughout the ... vertex. The constant coordinate assigned is then the label on ∆ counterclockwise
of the extra vertex, minus the label on ∆ clockwise of the extra vertex.
The v...
... me to the area of log-concave sequences.
Abstract
We provide a combinatorial proof for the fact that for any fixed n, the sequence
{i(n, k )}
0≤k ≤
(
n
2
)
of the numbers of permutations of length ... i(p) of inversions, and the study of numbers
i(n, k)ofn-permutations having k inversions, is a classic area of combinatorics. The
best-known result is the following...
... 1986.
the electronic journal of combinatorics 12 (2005), #R18 8
Theorem 2.3 (Aztec diamond theorem) The number of domino tilings of the Aztec
diamond of order n is 2
n(n+1)/2
.
Remark: The proof of ... Kirkland [2] give a proof by considering a matrix of order n(n +1)
the determinant of which gives a
n
. Their proof is reduced to the computation of the
dete...