empty set

音標(biāo)發(fā)音

Start from scratch: Start with an empty set of conditions and add your own.
從頭開始：從一組空的條件開始并添加您自己的條件。
This occurs because the fields are empty, so we are actually multiplying nothing by nothing (or empty set by empty set).
之所以會出現(xiàn)這個問題是由于字段是空的，因此實際上進行的計算是零乘零（或者空集乘空集）。
When you invoke a Groovy method that has no parameters, you must call it with an empty set of parentheses, which allows Groovy to distinguish between a property access from a method call.
當(dāng)您調(diào)用一個沒有參數(shù)的 Groovy 方法時，您必須使用一對空括號調(diào)用它，這使得 Groovy 可以分清一個屬性訪問和一個方法調(diào)用之間的區(qū)別。

Possibly an empty set of constraints.
約束條件得出的也可能是空值。
麻省理工公開課 - 計算機科學(xué)及編程導(dǎo)論課程節(jié)選

Picture this: a stately room full of empty chairs set up two rows deep in a semi circle.
FORBES: Women Politicians And Twitter Train Wrecks
As soon as Munin bullied him, he headed over to a set of empty containers, prised the lids off them enthusiastically, and pretended to eat.
ECONOMIST: Now, it seems, even the bird-brained have theories of mind

a set (= a group of numbers) that contains no elements, represented by the symbol {}