Hi guys I was first introduced to diagrammatic notation in Roger Penrose's book "Road to Reality". I wanted to know if any of you are familiar with diagrammatic notation for tensors? As such, is it worthwhile learning? Its certainly alot clearer (for me anyway :P) than index notation for some of the more complicated structures. I quite like the way contraction looks and a few of the graphical 'proofs' seem very natural (like the determinant of a product being the product of the determinants). As an aside: If you were to add two tensors of the same valence, what would the new structure look like? Thanks Jacques