diff --git a/magico.cabal b/magico.cabal
--- a/magico.cabal
+++ b/magico.cabal
@@ -1,5 +1,5 @@
 Name:                magico
-Version:             0.0.0.1
+Version:             0.0.1
 Synopsis:            Compute solutions for Magico puzzle
 Description:
   Compute solutions for Magico puzzle:
@@ -14,7 +14,7 @@
 Cabal-Version:       >=1.10
 
 Source-Repository this
-  Tag:         0.0.0.1
+  Tag:         0.0.1
   Type:        darcs
   Location:    http://hub.darcs.net/thielema/magico
 
@@ -26,8 +26,9 @@
   Main-is:             Main.hs
   Build-Depends:
     hmatrix >=0.16 && <0.17,
-    transformers >=0.3 && <0.4,
+    transformers >=0.3 && <0.5,
     utility-ht >=0.0 && <0.1,
     base >=4.5 && <4.6
   Hs-Source-Dirs:      src
   Default-Language:    Haskell2010
+  GHC-Options:         -Wall
diff --git a/src/Main.hs b/src/Main.hs
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -2,10 +2,12 @@
 Magico
 <http://www.spectra-verlag.de/>
 -}
+module Main where
+
 import qualified Numeric.Container as NC
 import qualified Data.Packed.Matrix as Matrix
 import qualified Data.Packed.Vector as Vector
-import Numeric.LinearAlgebra.HMatrix (null1, rank)
+import Numeric.LinearAlgebra.HMatrix (null1, nullspace, rank)
 import Numeric.LinearAlgebra ((<\>))
 import Data.Packed.Matrix (Matrix)
 import Data.Packed.Vector (Vector)
@@ -137,6 +139,9 @@
 
 ranks :: Triple (Triple Int)
 ranks = outerProduct (curry $ rank . snd . splittedMatrix) indices indices
+
+masks :: Triple (Triple (Matrix Double))
+masks = outerProduct (curry $ nullspace . snd . splittedMatrix) indices indices
 
 {-
 Vectors of the null space look like