In mathematics, an abelian category is a category in which morphisms and objects can be added and in which kernels and cokernels exist and have desirable properties.
例如一個22歲開始工作的人，到65歲才退休，工作43年，退休前60個月的投保薪資是最高級距4萬5,800元，若65歲退休就開始請領，每個月能領3萬0,526元，不過若能等到70歲才請領，每個月就能領到3.6萬元；如果想要月領4萬元，則必須勞保不退保，持續加保至70歲，就能每月領到4萬元老年年金。
