permute π₁Σ generators to maintain coherent order with Aut(F_n)

2021-07-07 10:34:42 +02:00 · 2021-07-07 10:34:42 +02:00 · 99fd238cf2
parent 3629b07626
commit 99fd238cf2
1 changed files with 8 additions and 3 deletions
--- a/src/groups/symplectic_twists.jl
+++ b/src/groups/symplectic_twists.jl
@ -155,10 +155,15 @@ function SymplecticMappingClass(

    g = sautFn(w)

-    d = ntuple(i->gens(Σ, i), ngens(Σ))
+    perm = let g = genus(Σ)
+        [reverse(1+1:2:2g); reverse(1:2:2g)]
+    end

-    img = evaluate!(deepcopy(d), g)
-    invim = evaluate!(d, inv(g))
+    d = ntuple(i->gens(Σ, i), ngens(Σ))[perm]
+
+
+    img = evaluate!(deepcopy(d), g)[invperm(perm)]
+    invim = evaluate!(d, inv(g))[invperm(perm)]

    img, invim = inverse ? (invim, img) : (img, invim)