The requirement that your turns sum to zero is necessary to keep you from getting caught in certain loops, such as one shaped like a capital G (try it out on paper to see what I mean).

转身数的总和必须是零，这是为了避免陷入某些环路，比如大写字母 G 形状的环路（在纸上试着走一下这个形状，就会明白我的意思）。

youdao

In so far as linear motion is concerned, a body is in equilibrium if the vector sum of the forces acting upon it is zero.

就线性运动而论，如果作用于严格物体上的诸力的矢量之和是零，那么这个物体就处于平衡状态。

youdao

BL: It's not a perfect zero-sum game.

伯恩·隆伯格：这并不完全是一个零和博弈。

youdao

So,after taking into account the market impact, and the commissions,and the fees, this zero-sum game becomes a negative-sum game.

所以,考虑到市场冲击,佣金,规费,这一零和博弈变成了负和博弈

耶鲁公开课 - 金融市场课程节选

First of all, happiness is a positive sum game-- it's not a zero sum game.

首先，快乐是正和游戏-,不是零和游戏。

哈佛公开课 - 幸福课课程节选

We've already talked about how security selection is a zero-sum game.

我们已经讨论过,证券选择是个零和博弈

耶鲁公开课 - 金融市场课程节选

The key work variable is zero-sum vs. non-zero sum (both negative-sum and positive-sum).

FORBES: The Fundamental 2x2 of Capitalism

The second eternal truth: Success is not a zero-sum game, though most academic economists, pundits and politicians act as if it were--maybe because they vie for glory in zero-sum professions. (There can be only 1 U.S. President and 100 senators, for example.) The third eternal truth: The Golden Rule is more than a spiritual truth, it is a business truth.

FORBES: Digital Rules

The virtue of HSAs, however, goes well beyond this semi-zero-sum mentality: The way health care is delivered will change as providers find it in their best interest to come up with inno-vative breakthroughs.

FORBES: Fact and Comment