encourage your classifier to say do you say that here's a bird here's a bird there's a bird right here hey hey there's a bird there's a bird there's a bird and basically just because the signal for that bird is stronger and basically ignore the other bird what you want to do is you want to encourage some sort of your classifier to detect if it has already detected an object it shouldn't detect again in a slightly different place so what the way you do this is with this bipartite matching loss so at the time when you compute the loss you go here