Identifier
-
Mp00201:
Dyck paths
—Ringel⟶
Permutations
Mp00071: Permutations —descent composition⟶ Integer compositions
Mp00184: Integer compositions —to threshold graph⟶ Graphs
St000422: Graphs ⟶ ℤ
Values
[1,0] => [2,1] => [1,1] => ([(0,1)],2) => 2
[1,0,1,0] => [3,1,2] => [1,2] => ([(1,2)],3) => 2
[1,0,1,0,1,0] => [4,1,2,3] => [1,3] => ([(2,3)],4) => 2
[1,1,0,1,0,0] => [4,3,1,2] => [1,1,2] => ([(1,2),(1,3),(2,3)],4) => 4
[1,0,1,0,1,0,1,0] => [5,1,2,3,4] => [1,4] => ([(3,4)],5) => 2
[1,1,0,1,0,0,1,0] => [5,3,1,2,4] => [1,1,3] => ([(2,3),(2,4),(3,4)],5) => 4
[1,1,0,1,0,1,0,0] => [5,4,1,2,3] => [1,1,3] => ([(2,3),(2,4),(3,4)],5) => 4
[1,1,1,1,0,0,0,0] => [2,3,4,5,1] => [4,1] => ([(0,4),(1,4),(2,4),(3,4)],5) => 4
[1,0,1,0,1,0,1,0,1,0] => [6,1,2,3,4,5] => [1,5] => ([(4,5)],6) => 2
[1,1,0,1,0,0,1,0,1,0] => [6,3,1,2,4,5] => [1,1,4] => ([(3,4),(3,5),(4,5)],6) => 4
[1,1,0,1,0,1,0,0,1,0] => [6,4,1,2,3,5] => [1,1,4] => ([(3,4),(3,5),(4,5)],6) => 4
[1,1,1,0,1,0,1,0,0,0] => [6,5,4,1,2,3] => [1,1,1,3] => ([(2,3),(2,4),(2,5),(3,4),(3,5),(4,5)],6) => 6
[1,1,1,1,0,0,0,0,1,0] => [2,3,4,6,1,5] => [4,2] => ([(1,5),(2,5),(3,5),(4,5)],6) => 4
[1,1,1,1,0,0,0,1,0,0] => [2,3,6,5,1,4] => [3,1,2] => ([(1,4),(1,5),(2,4),(2,5),(3,4),(3,5),(4,5)],6) => 6
[1,0,1,0,1,0,1,0,1,0,1,0] => [7,1,2,3,4,5,6] => [1,6] => ([(5,6)],7) => 2
[1,1,0,1,0,0,1,0,1,0,1,0] => [7,3,1,2,4,5,6] => [1,1,5] => ([(4,5),(4,6),(5,6)],7) => 4
[1,1,0,1,0,1,0,0,1,0,1,0] => [7,4,1,2,3,5,6] => [1,1,5] => ([(4,5),(4,6),(5,6)],7) => 4
[1,1,0,1,0,1,0,1,0,1,0,0] => [7,6,1,2,3,4,5] => [1,1,5] => ([(4,5),(4,6),(5,6)],7) => 4
[1,1,1,0,1,0,1,0,0,0,1,0] => [7,5,4,1,2,3,6] => [1,1,1,4] => ([(3,4),(3,5),(3,6),(4,5),(4,6),(5,6)],7) => 6
[1,1,1,1,0,0,0,0,1,0,1,0] => [2,3,4,7,1,5,6] => [4,3] => ([(2,6),(3,6),(4,6),(5,6)],7) => 4
[1,1,1,1,0,0,0,1,0,0,1,0] => [2,3,7,5,1,4,6] => [3,1,3] => ([(2,5),(2,6),(3,5),(3,6),(4,5),(4,6),(5,6)],7) => 6
[1,1,1,1,0,0,0,1,0,1,0,0] => [2,3,7,6,1,4,5] => [3,1,3] => ([(2,5),(2,6),(3,5),(3,6),(4,5),(4,6),(5,6)],7) => 6
[] => [1] => [1] => ([],1) => 0
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Description
The energy of a graph, if it is integral.
The energy of a graph is the sum of the absolute values of its eigenvalues. This statistic is only defined for graphs with integral energy. It is known, that the energy is never an odd integer [2]. In fact, it is never the square root of an odd integer [3].
The energy of a graph is the sum of the energies of the connected components of a graph. The energy of the complete graph $K_n$ equals $2n-2$. For this reason, we do not define the energy of the empty graph.
The energy of a graph is the sum of the absolute values of its eigenvalues. This statistic is only defined for graphs with integral energy. It is known, that the energy is never an odd integer [2]. In fact, it is never the square root of an odd integer [3].
The energy of a graph is the sum of the energies of the connected components of a graph. The energy of the complete graph $K_n$ equals $2n-2$. For this reason, we do not define the energy of the empty graph.
Map
Ringel
Description
The Ringel permutation of the LNakayama algebra corresponding to a Dyck path.
Map
descent composition
Description
The descent composition of a permutation.
The descent composition of a permutation $\pi$ of length $n$ is the integer composition of $n$ whose descent set equals the descent set of $\pi$. The descent set of a permutation $\pi$ is $\{i \mid 1 \leq i < n, \pi(i) > \pi(i+1)\}$. The descent set of a composition $c = (i_1, i_2, \ldots, i_k)$ is the set $\{ i_1, i_1 + i_2, i_1 + i_2 + i_3, \ldots, i_1 + i_2 + \cdots + i_{k-1} \}$.
The descent composition of a permutation $\pi$ of length $n$ is the integer composition of $n$ whose descent set equals the descent set of $\pi$. The descent set of a permutation $\pi$ is $\{i \mid 1 \leq i < n, \pi(i) > \pi(i+1)\}$. The descent set of a composition $c = (i_1, i_2, \ldots, i_k)$ is the set $\{ i_1, i_1 + i_2, i_1 + i_2 + i_3, \ldots, i_1 + i_2 + \cdots + i_{k-1} \}$.
Map
to threshold graph
Description
The threshold graph corresponding to the composition.
A threshold graph is a graph that can be obtained from the empty graph by adding successively isolated and dominating vertices.
A threshold graph is uniquely determined by its degree sequence.
The Laplacian spectrum of a threshold graph is integral. Interpreting it as an integer partition, it is the conjugate of the partition given by its degree sequence.
A threshold graph is a graph that can be obtained from the empty graph by adding successively isolated and dominating vertices.
A threshold graph is uniquely determined by its degree sequence.
The Laplacian spectrum of a threshold graph is integral. Interpreting it as an integer partition, it is the conjugate of the partition given by its degree sequence.
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