make this a gap package.

1 files changed, 26 insertions, 0 deletions

diff --git a/gap/subgroupladders.gd b/gap/subgroupladders.gd
new file mode 100644
index 0000000..0ba67e9
--- /dev/null
+++ b/gap/subgroupladders.gd
@@ -0,0 +1,26 @@
+#
+# subgroupladders: This package provides an algorithm that computes a subgroup ladder from a permutation group up to the parent symmetric group.
+#
+# Declarations
+#
+
+#! @Description
+#! Given a list of lists <A>part</A> of positive integers, this will compute 
+#! the Young #! subgroup corresponding to this partition.
+#! @Returns a group
+#! @Arguments part
+DeclareGlobalFunction( "YoungGroupFromPartition" );
+#! @Description
+#! Given a permutation group <A>G</A>, this will compute a subgroup ladder
+#! from <A>G</A> up to the parent symmetric group.
+#! A subgroup ladder is series of subgroups <M>G = H_0,…,H_k = S_n</M> of the 
+#! symmetric group such that for every <M>1 \leq i \leq k</M>, <M>H_i</M> is a 
+#! subgroup of <M>H_{{i-1}}</M> or <M>H_{{i-1}}</M> is a subgroup of <M>H_i</M>.
+#! If <A>G</A> is a Young subgroup of <M>S_n</M>, we can guarantee that all 
+#! the indices are at most the degree <M>n</M> of the permutation group. 
+#! Otherwise, we will at first embed <A>G</A> into the Young subgroup 
+#! corresponding to the orbits of <A>G</A>. 
+#! At this step, the index may be larger than the degree.
+#! @Returns a list of groups
+#! @Arguments G
+DeclareGlobalFunction( "SubgroupLadder");