What this equation merely says is that the present value of your remaining payments is always equal to the mortgage balance.

这个等式说明了,剩余偿还额的现值,就等于抵押贷款的余额

耶鲁公开课 - 金融市场课程节选

And so the value of with i will be the value of i plus whatever I can get using the remaining items and decrementing the weight by the weight of i.

所以装上i之后的总价值,就是i的价值加上剩下物品中,符合条件者的所有价值,再在剩余重量中减去i的重量。

麻省理工公开课 - 计算机科学及编程导论课程节选