diff --git a/src/DCB.hs b/src/DCB.hs
index 196e945..09cb74e 100644
--- a/src/DCB.hs
+++ b/src/DCB.hs
@@ -33,26 +33,31 @@ type Constraints = (Vector A.U Int, Matrix A.U Double)
 -- Graph consists of a Vector denoting which colums of the matrix represents wich originating
 -- column in the global adjencency-matrix, the reduces adjencency-matrix of the graph, a
 -- matrix of constraints and a scalar denoting the density
+type MaxDivergence = Vector A.U Double
 type Density = Double
 
 -- Graph
 type Graph = (Vector A.U Int, Constraints, Density)
 
-
+-- expand calculates all possible additions towards a vector of graphs
 expand :: Adj -> Attr -> [Graph] ->  [Graph]
-expand adj attr g = undefined
+expand adj attr g = undefined -- addablePoints -> for each: addPoint -> filterLayer
+
+-- filterLayer removes all duplicate graphs
+filterLayer :: Vector A.U Graph -> Vector A.U Graph
+filterLayer gs = undefined
 
 -- constraint gets a Graph and an Attribute-Matrix and yields true, if the Graph still fulfills
 -- all constraints defined via the Attribute-Matrix.
-constraint :: Adj -> Attr -> Graph -> Int -> Maybe Constraints
-constraint adj attr g newNode = undefined
+constraint :: Adj -> Attr -> MaxDivergence -> Int -> Graph -> Int -> Maybe Constraints
+constraint adj attr div req g newNode = undefined -- test each attribute -> sum -> test sum with req
 
 
 -- addPoint gets a graph and a tuple of an adjecancy-Vector with an int wich column of the
 -- Adjacency-Matrix the Vector should represent to generate further Graphs
-addPoint :: Adj -> Attr -> Density -> Graph -> Int -> Maybe Graph
-addPoint adj attr g c = undefined
+addPoint :: Adj -> Attr -> Density -> MaxDivergence -> Int -> Graph -> Int -> Maybe Graph
+addPoint adj attr d div req g c = undefined -- call constraint, test (updated) density
 
--- addablePoints yields all valid addititons to a Graph
+-- addablePoints yields all valid addititons (= neighbours) to a Graph
 addablePoints :: Adj -> Graph -> Vector A.U Int
 addablePoints adj g = undefined