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GraphVertexConnectivity ​

The fewest vertices whose deletion leaves a disconnected graph; the complete graph on n vertices gives n - 1.

✓ checked against that system · ! checked, with disagreements (hover a chip)FindStatSt000262via LabeledGraph✓
GraphVertexConnectivity(graph)The fewest vertices whose deletion leaves a disconnected graph; the complete graph on n vertices gives n - 1.
Typed signatures
TypePackageApplies
(labeled_graph) -> numbercombinatoricsalways

Domain: Graph statistics

Details
  • Defined over LabeledGraph as an expression in _x, evaluated by compute-engine — the definition IS the implementation.
  • Takes a LabeledGraph and nothing else — it reads values against their positions, or walks the orbits, so it needs the bijection. Applying it to a bare list is a type error, not a wrong answer.
  • FindStat's St000262. A disconnected graph gives 0. The graph with no vertices gives 0.

Definition

Epsil, as the implementation runs it.

on LabeledGraph, over _x

0 if _x[1] == 0 else Apply((n: integer) => Apply((edges: list<list<integer>>) => Apply(
                                                                                        (inside: list<integer>) => Apply(
                                                                                                                          (totals: list<integer>) => Apply(
                                                                                                                                                            (connected: list<integer>) => Min(Map(
                                                                                                                                                                                                   Function(totals[m + 1] if (1 if m <
                                                                                                                                                                                                                                   2 ^ n -
                                                                                                                                                                                                                                   1 else 0) *
                                                                                                                                                                                                                             (1 -
                                                                                                                                                                                                                              connected[2 ^ n -
                                                                                                                                                                                                                                        1 -
                                                                                                                                                                                                                                        m +
                                                                                                                                                                                                                                        1]) ==
                                                                                                                                                                                                                             1 else n - 1, m),
                                                                                                                                                                                                   Range(0, 2 ^ n -
                                                                                                                                                                                                            1),
                                                                                                                                                                                                 )),
                                                                                                                                                            Apply((a_init: list<integer>) => Fold((a: list<integer>, b) => Apply(
                                                                                                                                                                                                                                  (a_next: list<integer>) => a_next,
                                                                                                                                                                                                                                  Join(a, [1 if totals[b + 1] ==
                                                                                                                                                                                                                                                1 else Min(1, Max(Sum(Map(Function(a[b -
                                                                                                                                                                                                                                                                                    2 ^
                                                                                                                                                                                                                                                                                    (v - 1) +
                                                                                                                                                                                                                                                                                    1] *
                                                                                                                                                                                                                                                                                  (1 if inside[b + 1] -
                                                                                                                                                                                                                                                                                        inside[b -
                                                                                                                                                                                                                                                                                               2 ^
                                                                                                                                                                                                                                                                                               (v - 1) +
                                                                                                                                                                                                                                                                                               1] >
                                                                                                                                                                                                                                                                                        0 else 0) if b %
                                                                                                                                                                                                                                                                                      2 ^ v >=
                                                                                                                                                                                                                                                                                      2 ^
                                                                                                                                                                                                                                                                                      (v - 1) else 0, v), Range(1, n))), 0))]),
                                                                                                                                                                                                                                ), a_init, Range(1, 2 ^ n -
                                                                                                                                                                                                                                                   1)), [0]),
                                                                                                                                                          ),
                                                                                                                          Map(
                                                                                                                               Function(Max(Sum(Map(Function(1 if m %
                                                                                                                                                                  2 ^ v >=
                                                                                                                                                                  2 ^
                                                                                                                                                                  (v - 1) else 0, v), Range(1, n))), 0), m),
                                                                                                                               Range(0, 2 ^ n -
                                                                                                                                        1),
                                                                                                                             ),
                                                                                                                        ),
                                                                                        Map(
                                                                                             Function(Max(Sum(Map(Function((1 if m %
                                                                                                                                 2 ^ e[1] >=
                                                                                                                                 2 ^
                                                                                                                                 (e[1] - 1) else 0) *
                                                                                                                           (1 if m %
                                                                                                                                 2 ^ e[2] >=
                                                                                                                                 2 ^
                                                                                                                                 (e[2] - 1) else 0), e), edges)), 0), m),
                                                                                             Range(0, 2 ^ n -
                                                                                                      1),
                                                                                           ),
                                                                                      ), _x[2]), _x[1])

Examples

Basic #

the graph on 4 vertices with the edges 12, 23, 24 and 34

live ↗
InGraphVertexConnectivity(LabeledGraph⁡((4,[[1,2],[2,3],[2,4],[3,4]])))\mathrm{GraphVertexConnectivity}(\operatorname{LabeledGraph}((4,\bigl\lbrack\bigl\lbrack1, 2\bigr\rbrack, \bigl\lbrack2, 3\bigr\rbrack, \bigl\lbrack2, 4\bigr\rbrack, \bigl\lbrack3, 4\bigr\rbrack\bigr\rbrack)))Out11
Properties #

FindStat's value for ([],1)

live ↗
InCombinatorialStat(LabeledGraph⁡((1,[])),GraphVertexConnectivity)\mathrm{CombinatorialStat}(\operatorname{LabeledGraph}((1,\bigl\lbrack\bigr\rbrack)), \text{GraphVertexConnectivity})Out00

Known value · FindStat St000262

FindStat's value for ([],2)

live ↗
InCombinatorialStat(LabeledGraph⁡((2,[])),GraphVertexConnectivity)\mathrm{CombinatorialStat}(\operatorname{LabeledGraph}((2,\bigl\lbrack\bigr\rbrack)), \text{GraphVertexConnectivity})Out00

Known value · FindStat St000262

FindStat's value for ([],3)

live ↗
InCombinatorialStat(LabeledGraph⁡((3,[])),GraphVertexConnectivity)\mathrm{CombinatorialStat}(\operatorname{LabeledGraph}((3,\bigl\lbrack\bigr\rbrack)), \text{GraphVertexConnectivity})Out00

Known value · FindStat St000262

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