名词 sum:

1. a quantity of money

2. a quantity obtained by the addition of a group of numbers

3. the final aggregate

4. the choicest or most essential or most vital part of some idea or experience

5. the whole amount

6. a set containing all and only the members of two or more given sets

sumn.金额；总数；要点v.概括；总结；归纳；总计sumupn.总计；总结；概括

1. The operation of summing is represented by the nodes.
   求和的运算是通过节点来表示的。