sclass OneColorTheory {
  replace Cell with URecognizer.Cell.
  
  Theory makeOneColorTheory(Cell cell) {
    var color = cell.averageColor();

    var theory = postIdea("Color of every pixel in $cell is $color.", +cell, +color);
  
    testOneColorTheory(cell, theory);
    ret theory;
  }

  void noteCellColor(cell, theory) {
    var desc = "Pixel check at " + cell;
    if (theory.hasExampleNamed(desc)) return;
    var strength = doubleRatio(cell.area(), theory.cell.area()); // how much do we have to say about the cell in the theory?
    var p = colorDistanceToProbability(cell.averageColor(), theory.color);
    addExampleToTheory(theory, desc, p, strength);
  }
  
  double colorDistanceToProbability(RGB col1, RGB col2) {
    ret sqr(colorSimilarity(col1, col2));
  }
  
  void testOneColorTheory(cell, theory) {  
    noteCellColor(cell, theory);
  
    at shouldSplitCell(cell) do:
      for split, splitProbability in usefulSplits(cell):
        at splitProbability do:
          for cell in split:
            testOneColorTheory(cell, theory/*.branch(description := "recursion to " + cell)*/);
  }
}