Recommender system for "single-use items"

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Let's say I have a system to which customers can create new items, or tasks. Each task consists of parameters, like what type of task it is (categorical), when it should be completed (time window), what type of customer created it (categorical), and so on. Then I have users who can take these items, or be assigned to the tasks. The thing is that only one user can take any particular task.