## 1 Introduction
### Related Works  
Many of the large-scale companies engaged in delivery and transportation businesses already use drones in their transportation operations. With the Prime Air system introduced by Amazon, it is planned to deliver packages to customers in thirty minutes or less using drones. The first delivery of Prime Air was completed on 7 December 2016 in thirteen minutes [17]. In a study carried out by [PERSON], [PERSON], and [PERSON] (DHL), a logistics company, deliveries were made using drones. In the tests, in which drugs were delivered to an island on Lake Victoria for six months with the drone they named Parcelcopter, the drone was able to cover the sixty-kilometer distance between the mainland and the island in forty minutes. At the end of six months, this drone had flown a total of 2200 km [18]. Swiss Post, a Swiss postal service, started to transmit laboratory samples using drones,which were previously transmitted by land, and thus managed to reduce the transmission time from up to 45 min to a few minutes. This development has resulted in much faster delivery of healthcare shipments that often need urgent delivery [19]. In Turkey, companies are also working on and making breakthroughs in the use of drones in their deliveries. In addition, studies on truck-drone delivery and route optimization have also found important places in the literature. These studies mostly consisted of different variations of TSP and VRP, which included solution methods for different scenarios. These scenarios, in which it is aimed to find the optimum route for truck-drone delivery, are considered problems, and many of them are defined as \"NP-hard\"; that is, they are difficult to solve. Generally, heuristic methods and dynamic programming methods have been proposed as solutions to such problems [20; 21; 22; 23; 24; 25; 26]. A genetic algorithm (GA) is one of the heuristic methods, and it is an algorithm created by applying the idea of natural selection in a computer environment. According to the GA, in each new generation, individuals with high-quality and low-quality genes from the previous generation and the most appropriate distribution of traits survive, but incompetent individuals cannot. In this way, the tendency for good and strong traits to be seen in new generations is greater [27; 28; 29; 30]. Truck-drone delivery is basically the delivery of trucks and drones working together in delivery operations. These operations can have different scenarios. For example, one scenario may contain only one truck and one drone, while another scenario may not limit the number of trucks and drones. Or, in one scenario, while the drone moves from the warehouse independently of the truck and returns to the warehouse after completing the delivery, in another scenario, the truck and the drone may be considered as a whole, and the drone may not be allowed to operate independently of the truck. Since many different scenarios can be created in such studies, there are different scenarios for different operations in the literature. In The Flying Sidekick Traveling Salesman Problem (FSTSP), a study by [PERSON] et al., deliveries were realized by one truck and one drone. According to the scenario of FSTSP, the drone, which can carry a single package, left the truck when the time came and met the truck at the next stop of the moving truck after delivery. This study aimed to minimize the time until the return to the warehouse, i.e., the total delivery time. This was an NP-hard problem. Heuristic methods were proposed to solve this problem because it is an NP-hard problem. In the same study, it was suggested that delivery to remote locations can be executed by truck if most of the delivery points are close to the warehouse. It has also been suggested that drones can complete the delivery by constantly commuting between the central warehouse and nearby points and delivering to locations close to the central warehouse. This scenario was called the Parallel Drone Scheduling Traveling Salesman Problem (PDSTSP).