diff --git a/som.cabal b/som.cabal
--- a/som.cabal
+++ b/som.cabal
@@ -1,5 +1,5 @@
 name:           som
-version:        6.4
+version:        6.5.1
 synopsis:       Self-Organising Maps
 description:    A Kohonen Self-organising Map (SOM) maps input patterns 
                 onto a regular grid (usually two-dimensional) where each
@@ -29,8 +29,8 @@
   hs-source-dirs:  src
   build-depends:   base ==4.*,
                    base-unicode-symbols ==0.2.*,
-                   binary == 0.5.* || == 0.6.* || == 0.7.*,
-                   containers ==0.4.2.* || ==0.5.*,
+                   binary ==0.7.*,
+                   containers ==0.5.*,
                    grid ==7.*,
                    MonadRandom ==0.1.*
   ghc-options:     -Wall
@@ -45,8 +45,8 @@
   type:            exitcode-stdio-1.0
   build-depends:   base ==4.*,
                    test-framework-quickcheck2 == 0.3.*,
-                   QuickCheck ==2.5.* || ==2.6.*,
-                   test-framework == 0.8.*,
+                   QuickCheck ==2.6.*,
+                   test-framework ==0.8.*,
                    som,
                    grid ==7.*,
                    base-unicode-symbols ==0.2.*,
diff --git a/src/Data/Datamining/Clustering/SOMInternal.hs b/src/Data/Datamining/Clustering/SOMInternal.hs
--- a/src/Data/Datamining/Clustering/SOMInternal.hs
+++ b/src/Data/Datamining/Clustering/SOMInternal.hs
@@ -209,6 +209,8 @@
 --
 --   * 0 < wf << w0
 --
+--   * 0 < tf
+--
 --   where << means "is much smaller than" (not the Haskell @<<@
 --   operator!) 
 decayingGaussian2 :: Floating a => a -> a -> a -> a -> Int -> (Int -> Int -> a)