Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: What are the names of the technicians that have not been assigned to repair machines? | repair : repair_id , name , launch_date , notes | machine : machine_id , making_year , class , team , machine_series , value_points , quality_rank | technician : technician_id , name , team , starting_year , age | repair_assignment : technician_id , repair_id , machine_id | repair_assignment.machine_id = machine.machine_id | repair_assignment.repair_id = repair.repair_id | repair_assignment.technician_id = technician.technician_id | 

### Response:

select _ from _ where _ not in ( select _ from _ ) | select name from technician where technician_id not in ( select technician_id from repair_assignment )