STSP seeks a pair of pickup and delivery tours in two distinct networks, where the two tours are related by LIFO contraints. We address here the problem approximability. We notably establish that asymmetric MaxSTSP and MinSTSP12 are APX, and propose a heuristic that yields to a 1/2, 3/4 and 3/2 standard approximation for respectively Max2STSP, Max2STSP12 and Min2STSP12.

Last mile logistics represent one of the most important challenging issues in online grocery shopping. Online customers are expecting high logistical services, demanding convenience, high reliable and on-time delivery services. As such, online retailers have to respond to these expectations by providing convenient logistical services while keeping this process cost efficient as much as possible...

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) has a page devoted to updates state alcohol policies adopted in response the pandemic, but it no information effects of these policies, which include expanded home delivery, curbside pickup, to-go cocktails, more. were meant limit virus exposure.

Multi-Agent Path Finding (MAPF) problem is an extended class of pathfinding problems where multiple paths are assigned to agents without collision. MAPF can been applied various practical domains including path-planning robot carriers in warehouses, automated taxiing airplanes, and video games. Multi Agent Pickup Delivery (MAPD) that a continuous has studied for more cases such as warehouses wh...