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# monodromyGroup -- compute the group of permutations implicitly defined by a homotopy graph

## Synopsis

• Usage:
monodromyGroup S
monodromyGroup(S, p0, x0s)
• Inputs:
• S, an instance of the type System,
• p0, , a basepoint for the monodromy group in the parameter space for S
• x0s, a list, points in the fiber over S
• Optional inputs:
• FileName (missing documentation) => , default value null, a name for an output file suitable for reading by GAP. Default value is null.
• msOptions
• RootCount

## Description

If the monodromy group is full symmetric and the degree is large, then the default settings have a good chance of generating the whole group. However, you will need to use a bigger graph than the default settings to fully generate imprimitive groups, as in the following example of a Euclidean distance degree calculation.

 i1 : setRandomSeed 100; i2 : declareVariable \ {t_1,t_2,u_0,u_1,u_2,u_3}; i3 : paramMatrix = gateMatrix{{u_0,u_1,u_2,u_3}}; i4 : varMatrix = gateMatrix{{t_1,t_2}}; i5 : phi = transpose gateMatrix{{t_1^3, t_1^2*t_2, t_1*t_2^2, t_2^3}}; i6 : loss = sum for i from 0 to 3 list (u_i - phi_(i,0))^2; i7 : dLoss = diff(varMatrix, gateMatrix{{loss}}); i8 : G = gateSystem(paramMatrix,varMatrix,transpose dLoss); i9 : monodromyGroup(G,"msOptions" => {NumberOfEdges=>10}) o9 = {{0, 1, 7, 17, 12, 18, 2, 19, 11, 8, 10, 20, 5, 13, 14, 3, 16, 15, 6, 9, ------------------------------------------------------------------------ 4}, {0, 9, 2, 3, 10, 5, 14, 7, 8, 1, 4, 11, 12, 13, 6, 15, 16, 17, 18, ------------------------------------------------------------------------ 19, 20}, {0, 1, 7, 17, 12, 18, 2, 19, 11, 8, 10, 20, 5, 13, 14, 3, 16, ------------------------------------------------------------------------ 15, 6, 9, 4}, {16, 1, 7, 17, 12, 18, 2, 19, 11, 8, 10, 20, 5, 0, 14, 3, ------------------------------------------------------------------------ 13, 15, 6, 9, 4}, {0, 11, 2, 3, 10, 4, 14, 6, 8, 1, 5, 9, 12, 13, 7, 15, ------------------------------------------------------------------------ 16, 17, 18, 19, 20}, {0, 1, 2, 3, 4, 11, 6, 5, 8, 9, 10, 7, 12, 13, 14, ------------------------------------------------------------------------ 15, 16, 17, 18, 19, 20}, {12, 1, 7, 17, 16, 9, 0, 4, 11, 13, 10, 6, 5, ------------------------------------------------------------------------ 2, 14, 3, 8, 15, 20, 18, 19}, {0, 9, 2, 3, 10, 5, 14, 7, 8, 1, 4, 11, ------------------------------------------------------------------------ 12, 13, 6, 15, 16, 17, 18, 19, 20}, {0, 1, 2, 3, 9, 11, 4, 5, 8, 6, 10, ------------------------------------------------------------------------ 7, 12, 13, 14, 15, 16, 17, 18, 19, 20}, {12, 1, 3, 19, 0, 11, 13, 5, 15, ------------------------------------------------------------------------ 16, 10, 7, 17, 2, 14, 20, 8, 18, 9, 4, 6}, {0, 1, 3, 19, 12, 11, 2, 5, ------------------------------------------------------------------------ 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, 6}, {12, 16, 14, 17, 4, 7, ------------------------------------------------------------------------ 6, 11, 1, 9, 0, 5, 10, 2, 13, 3, 8, 15, 20, 18, 19}, {0, 1, 3, 19, 12, ------------------------------------------------------------------------ 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, 6}, {0, 1, 3, 19, ------------------------------------------------------------------------ 12, 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, 6}, {17, 16, ------------------------------------------------------------------------ 14, 9, 8, 7, 12, 11, 1, 2, 0, 5, 10, 3, 13, 4, 15, 6, 20, 18, 19}, {12, ------------------------------------------------------------------------ 16, 14, 19, 4, 3, 6, 15, 1, 9, 0, 17, 10, 2, 13, 20, 8, 18, 7, 11, 5}, ------------------------------------------------------------------------ {12, 16, 3, 19, 10, 11, 14, 5, 15, 1, 0, 7, 17, 2, 13, 20, 8, 18, 9, 4, ------------------------------------------------------------------------ 6}, {0, 1, 3, 19, 12, 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, ------------------------------------------------------------------------ 4, 6}, {12, 16, 14, 19, 4, 7, 6, 11, 1, 9, 0, 5, 10, 2, 13, 20, 8, 18, ------------------------------------------------------------------------ 3, 15, 17}, {12, 16, 7, 17, 10, 9, 14, 4, 11, 1, 0, 6, 5, 2, 13, 3, 8, ------------------------------------------------------------------------ 15, 20, 18, 19}, {2, 0, 9, 3, 10, 5, 14, 7, 4, 1, 13, 11, 6, 8, 16, 15, ------------------------------------------------------------------------ 12, 17, 18, 19, 20}, {3, 16, 12, 4, 10, 11, 14, 5, 2, 1, 0, 7, 8, 15, ------------------------------------------------------------------------ 13, 6, 17, 9, 18, 19, 20}, {2, 0, 9, 3, 10, 5, 14, 7, 4, 1, 13, 11, 6, ------------------------------------------------------------------------ 8, 16, 15, 12, 17, 18, 19, 20}, {0, 1, 2, 20, 6, 5, 9, 7, 8, 4, 10, 11, ------------------------------------------------------------------------ 12, 13, 14, 18, 16, 19, 15, 17, 3}, {12, 16, 7, 17, 10, 9, 14, 4, 11, 1, ------------------------------------------------------------------------ 0, 6, 5, 2, 13, 3, 8, 15, 20, 18, 19}, {0, 1, 2, 20, 6, 5, 9, 7, 8, 4, ------------------------------------------------------------------------ 10, 11, 12, 13, 14, 18, 16, 19, 15, 17, 3}, {0, 1, 2, 20, 6, 5, 9, 7, 8, ------------------------------------------------------------------------ 4, 10, 11, 12, 13, 14, 18, 16, 19, 15, 17, 3}, {2, 0, 9, 3, 10, 5, 14, ------------------------------------------------------------------------ 7, 4, 1, 13, 11, 6, 8, 16, 15, 12, 17, 20, 18, 19}, {1, 16, 12, 19, 11, ------------------------------------------------------------------------ 15, 5, 17, 2, 7, 0, 3, 8, 10, 13, 20, 14, 18, 9, 4, 6}, {12, 16, 7, 17, ------------------------------------------------------------------------ 10, 9, 14, 4, 11, 1, 0, 6, 5, 2, 13, 3, 8, 15, 18, 19, 20}, {1, 16, 12, ------------------------------------------------------------------------ 19, 11, 15, 5, 17, 2, 7, 0, 3, 8, 10, 13, 20, 14, 18, 9, 4, 6}, {2, 0, ------------------------------------------------------------------------ 11, 3, 10, 4, 14, 6, 5, 1, 13, 9, 7, 8, 16, 15, 12, 17, 18, 19, 20}, {0, ------------------------------------------------------------------------ 1, 2, 20, 6, 5, 9, 7, 8, 4, 10, 11, 12, 13, 14, 18, 16, 19, 15, 17, 3}, ------------------------------------------------------------------------ {3, 1, 12, 4, 0, 11, 13, 5, 2, 16, 10, 7, 8, 15, 14, 6, 17, 9, 18, 19, ------------------------------------------------------------------------ 20}, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, ------------------------------------------------------------------------ 19, 20}, {0, 14, 12, 19, 11, 15, 5, 17, 2, 7, 1, 3, 8, 13, 10, 20, 16, ------------------------------------------------------------------------ 18, 9, 4, 6}, {2, 1, 0, 3, 4, 5, 6, 7, 13, 9, 10, 11, 16, 8, 14, 15, 12, ------------------------------------------------------------------------ 17, 18, 19, 20}, {0, 1, 3, 19, 12, 5, 2, 7, 15, 8, 10, 11, 17, 13, 14, ------------------------------------------------------------------------ 20, 16, 18, 9, 4, 6}, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ------------------------------------------------------------------------ 15, 16, 17, 18, 19, 20}, {16, 14, 17, 18, 8, 7, 12, 11, 3, 2, 1, 5, 15, ------------------------------------------------------------------------ 0, 10, 19, 13, 20, 6, 9, 4}, {4, 1, 2, 3, 0, 5, 13, 7, 8, 16, 10, 11, ------------------------------------------------------------------------ 12, 6, 14, 15, 9, 17, 18, 19, 20}, {0, 1, 3, 19, 12, 11, 2, 5, 15, 8, ------------------------------------------------------------------------ 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, 6}, {3, 16, 14, 4, 5, 2, 7, 8, 1, ------------------------------------------------------------------------ 11, 0, 12, 10, 15, 13, 6, 17, 9, 18, 19, 20}, {0, 1, 3, 19, 12, 11, 2, ------------------------------------------------------------------------ 5, 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, 6}, {4, 16, 14, 3, 5, 2, ------------------------------------------------------------------------ 7, 8, 1, 11, 0, 12, 10, 6, 13, 15, 9, 17, 18, 19, 20}, {16, 14, 17, 18, ------------------------------------------------------------------------ 8, 7, 12, 11, 3, 2, 1, 5, 15, 0, 10, 19, 13, 20, 6, 9, 4}, {0, 1, 2, 3, ------------------------------------------------------------------------ 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}, {16, 7, ------------------------------------------------------------------------ 12, 19, 9, 1, 4, 10, 2, 6, 11, 14, 8, 0, 5, 20, 13, 18, 3, 15, 17}, {2, ------------------------------------------------------------------------ 0, 1, 3, 6, 5, 9, 7, 10, 4, 13, 11, 14, 8, 16, 15, 12, 17, 18, 19, 20}, ------------------------------------------------------------------------ {0, 1, 3, 19, 12, 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, 20, 16, 18, 9, 4, ------------------------------------------------------------------------ 6}, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, ------------------------------------------------------------------------ 19, 20}, {16, 14, 17, 18, 8, 7, 12, 11, 3, 2, 1, 5, 15, 0, 10, 19, 13, ------------------------------------------------------------------------ 20, 6, 9, 4}, {0, 1, 3, 19, 12, 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, 20, ------------------------------------------------------------------------ 16, 18, 9, 4, 6}, {0, 1, 3, 19, 12, 11, 2, 5, 15, 8, 10, 7, 17, 13, 14, ------------------------------------------------------------------------ 20, 16, 18, 9, 4, 6}, {1, 7, 12, 19, 16, 4, 0, 6, 2, 13, 11, 9, 8, 10, ------------------------------------------------------------------------ 5, 20, 14, 18, 3, 15, 17}} o9 : List

## Caveat

This is still somewhat experimental.

## Ways to use monodromyGroup :

• monodromyGroup(System)
• monodromyGroup(System,AbstractPoint,List)
• monodromyGroup(HomotopyGraph) (missing documentation)

## For the programmer

The object monodromyGroup is .