A Simple Picture of String Scattering

You can really make this into very precise mathematics. You haveto, let's see, let's eme just pin this and lable. So im let me draw two pictures of string scattering. Here we have a, b goes to c d. Ka, slightly further way. No, there's no difference between these pictures because what we do when we compute this process is we actually have to re fix the initial and final strings,. We sum over all world sheets that go in between. Ah, we're to both. Is that sorted?