From 3a88728e0ac8ea1ab0f9a4cca8a7b4bbc7096bdb Mon Sep 17 00:00:00 2001
From: Marek Kaluba <kalmar@amu.edu.pl>
Date: Wed, 26 May 2021 12:12:26 +0200
Subject: [PATCH] add New.FreeGroup(n::Integer) method

---
 src/new_types.jl | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/new_types.jl b/src/new_types.jl
index 9057d54..aff0f87 100644
--- a/src/new_types.jl
+++ b/src/new_types.jl
@@ -134,6 +134,18 @@ function FreeGroup(A::Alphabet)
     return FreeGroup(KnuthBendix.letters(A), A)
 end
 
+function FreeGroup(n::Integer)
+    symbols = Symbol[]
+    inverses = Int[]
+    sizehint!(symbols, 2n)
+    sizehint!(inverses, 2n)
+    for i in 1:n
+        push!(symbols, Symbol(:f, i), Symbol(:F, i))
+        push!(inverses, 2i, 2i-1)
+    end
+    return FreeGroup(symbols[1:2:2n], Alphabet(symbols, inverses))
+end
+
 Base.show(io::IO, F::FreeGroup) = print(io, "free group on $(ngens(F)) generators")
 
 # mandatory methods: