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WeylGroups :: intervalBruhat(WeylGroupLeftCoset,WeylGroupLeftCoset)

intervalBruhat(WeylGroupLeftCoset,WeylGroupLeftCoset) -- elements between two given ones for the Bruhat order on a quotient of a Weyl group

Synopsis

Description

i1 : R=rootSystemA(3)

o1 = RootSystem{...8...}

o1 : RootSystem
i2 : P=parabolic(R,set {3})

o2 = set {3}

o2 : Parabolic
i3 : w1 = reduce(R,{2})

o3 = WeylGroupElement{RootSystem{...8...}, | 2  |}
                                           | -1 |
                                           | 2  |

o3 : WeylGroupElement
i4 : w2 = reduce(R,{1,2,1,3,2})

o4 = WeylGroupElement{RootSystem{...8...}, | -1 |}
                                           | -2 |
                                           | 1  |

o4 : WeylGroupElement
i5 : myInterval=intervalBruhat(w1 % P,w2 % P)

o5 = HasseDiagram{{{WeylGroupElement{RootSystem{...8...}, | 1  |}, {{0, | 1 |}, {1, | -1 |}}}}, {{WeylGroupElement{RootSystem{...8...}, | -2 |}, {{0, | -1 |}, {2, | 1  |}}}, {WeylGroupElement{RootSystem{...8...}, | -1 |}, {{0, | 2  |}, {1, | -1 |}}}}, {{WeylGroupElement{RootSystem{...8...}, | -2 |}, {{0, | 1  |}}}, {WeylGroupElement{RootSystem{...8...}, | 1  |}, {{0, | 2  |}}}, {WeylGroupElement{RootSystem{...8...}, | 2  |}, {{0, | -1 |}}}}, {{WeylGroupElement{RootSystem{...8...}, | 2  |}, {}}}}
                                                          | -3 |        | 0 |       | 1  |                                              | 3  |        | 1  |       | 1  |                                            | -1 |        | -1 |       | 2  |                                              | 1  |        | 1  |                                            | -2 |        | -1 |                                            | 1  |        | 1  |                                              | -1 |
                                                          | 1  |        | 1 |       | 1  |                                              | -2 |        | 1  |       | -1 |                                            | 3  |        | 0  |       | -1 |                                              | 2  |        | -1 |                                            | 3  |        | 0  |                                            | -2 |        | 1  |                                              | 2  |

o5 : HasseDiagram

Each row of the Hasse diagram contains the elements of a certain length together with their links to the next row.

i6 : myInterval#1

o6 = {{WeylGroupElement{RootSystem{...8...}, | -2 |}, {{0, | -1 |}, {2, | 1 
                                             | 3  |        | 1  |       | 1 
                                             | -2 |        | 1  |       | -1
     ------------------------------------------------------------------------
     |}}}, {WeylGroupElement{RootSystem{...8...}, | -1 |}, {{0, | 2  |}, {1,
     |                                            | -1 |        | -1 |      
     |                                            | 3  |        | 0  |      
     ------------------------------------------------------------------------
     | -1 |}}}}
     | 2  |
     | -1 |

o6 : List