Spatial crowdsourcing is an effective and novel method. In crowdsourcing systems. a centralized platform is traditionally used to allocate tasks and select workers. Centralized platforms always face following challenges: 1) How to ensure the rationality of tasks allocating; 2) How to ensure the payments of workers in the system when dishonest requesters exist; 3) How to ensure the max... https://www.jmannino.com/top-sale-Elf-Smiling-is-my-Favorite-Apple-AirPods-2-Skin-p16001-great-offer/