This problem is an example of what is called two-sided noncompliance (see chapter 6 of Gerber and Green (2012)).
ບັນຫານີ້ແມ່ນຕົວຢ່າງຂອງສິ່ງທີ່ເອີ້ນວ່າ ການບໍ່ປະຕິບັດສອງຝ່າຍ (ເບິ່ງພາກ 6 ຂອງ Gerber and Green (2012)).