anchor.diff:      |> Seq.map (fun t -> float t.Relevance)
       |> Seq.toArray
   
  -let testInput = 
  -    test.Rows 
  -    |> Seq.map (fun w -> wordMatch w.Search_term w.Product_title (productDescription w.Product_uid) |> toFloatArray)
  -    |> Seq.toArray
  -
   let target = MultipleLinearRegression(3, true)
   let sumOfSquaredErrors = target.Regress(trainInput, trainOutput)
   let observationCount = trainInput |> Seq.length |> float
   let sme = sumOfSquaredErrors / observationCount
   let rsme = sqrt(sme)
  +//0.49665 - stemmed
  +//0.5063 - string contains
  +
  +//0.50783 - kaggle reported
  +
  +let testInput = 
  +    test.Rows 
  +    |> Seq.map (fun w -> stringContainsMatch w.Search_term w.Product_title (productDescription w.Product_uid) |> toFloatArray)
  +    |> Seq.toArray
   
   let testOutput = target.Compute(testInput)
   
  
positive.code:     if stemmed.Length < word.Length then stemmed // HACK workaround stemmer output like "vanity" -> "vaniti"
      else word
  
  let wordMatch (words:string) (title:string) (desc:string) =
      let isMatch input word =
          let word' = stem word |> Regex.Escape // TODO strip punctuation?
          Regex.IsMatch(input, sprintf @"\b%s" word', RegexOptions.IgnoreCase)
  
negative.code:     let numberInDescription = uniqueWords |> Array.filter (isMatch desc) |> Array.length
      numberInTitle, numberInDescription, uniqueWords.Length 
  
  let stringContainsMatch (words:string) (title:string) (desc:string) =
      let words' = words.Split(' ')
      let uniqueWords = words' |> Array.distinct
      let numberInTitle = uniqueWords |> Array.filter (fun w -> title.ToLower().Contains(w.ToLower())) |> Array.length
      let numberInDescription = uniqueWords |> Array.filter (fun w -> desc.ToLower().Contains(w.ToLower())) |> Array.length
      numberInTitle, numberInDescription, uniqueWords.Length 
  
  let inline toFloatArray (a,b,c) = [| float a; float b; float c |]
  
  let trainInput = 
      train.Rows
      |> Seq.map (fun w -> stringContainsMatch w.Search_term w.Product_title (productDescription w.Product_uid) |> toFloatArray)
      |> Seq.toArray
  
  let trainOutput = 
  