Waitrose is the latest retailer to recruit UK start-up On the Dot for same day deliveries, using machine learning to optimize routes. The supermarket group joins 100 customers including Wickes, ASOS, Curry’s PC World, and Dixons, many fighting to compete over time to delivery with Amazon. On the Dot has attracted investment of £17.7mn ($23mn) since its launch in 2015, including a recent £8mn injection from its parent company City Sprint Group. Its selling point is use of machine learning to optimize the solution for the travelling salesman problem, a long-standing challenge in mathematical graph and optimization theory. With a fleet of 5000 couriers including bike and vans, the service offers hope to retailers of all sizes of avoiding having…