anchor.diff:  open Slp.Evi.Relational.Algebra
   open Slp.Evi.Relational.RelationalAlgebraOptimizers
   open Slp.Evi.R2RML.MappingTemplate
  +open Slp.Evi.Common.Algebra
   
   let rec private isBaseValueBinderBoundCondition neededVars =
       if neededVars |> Map.isEmpty then
  
positive.code:             neededVariables
              |> List.map (
                  fun var ->
                      var, source |>SqlSource.getColumn var |> Column
              )
              |> Map.ofList
  
  
negative.code:                     None
                  
              mayBeUsableSource
              |> Option.map (
                  fun x -> x, sqlSources
              )
              |> Option.defaultWith (fun () ->
                  let newSource =
                      {
                          Schema = schema
                          Columns =
                              schema.Columns
                              |> Seq.toList
                              |> List.map (fun col -> { Schema = schema.GetColumn(col) })
                      }
                  let updatedSources = newSource :: (sqlSources |> Map.tryFind pattern |> Option.defaultValue List.empty)
                  newSource, sqlSources |> Map.add pattern updatedSources
              )
  
          | Statement _ -> "SQL Statements are not yet supported" |> NotImplementedException |> raise
  
      let applyPatternMatch filters (valueBindings: Map<_,_>) source pattern mapping =
          let variables =
  