What are the written simplified chinese characters for "if and only if"

Question

In the English language, there is a phrase "if and only if"

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The last snow 🌨 ❄ of late winter in the state of Colorado (the red state) shall kill vegetable seedlings 🌱 if and only if fewer than 8 lunar cycles have passed since the first snow of fall or early winter.

What is a simplified manderin phrase for "if and only if" in this context involving snow killing edible plants.

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Example of multiples of ten

for any number x

x is a multiple of ten

if and only if x is a multiple of 5 and the number is a multiple of 2).

What is the manderine phrase for if and only if in the context of numbers?

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Example of a car in the middle of an intersection

for each car or automobile x

Car x is located where two or more roads cross, collide, or intersect.

if and only if only if there is number n ≥ 3 and
there are two decimal numbers d1 and d3 such that. for any decimal number d2
if 0 < d1 < d2 < d3 then for any circle with radius d2

there are n segments of this circle lying on a road.

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An Example that speaks of slow-made, quality work

For example, if you do quality work, you work very slowly. However, if you work very slowly, it does not mean that you will produce quality work.

It is false that, for any type of work, x, x is quality work if and only if x is slow work.

For example, I know how to paint a house very slowly and do a bad job. I do not know how to do good quality painting, but if I knew how to do a good quality paint job on a house, then it would take me a long time to paint that house.

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What was the question?

What is the simplified chinese expression for "if and only if" or .ay e the word "equivilantly?

Answer 1

当且仅当

当且仅当（英语：if and only if，iff），在数字逻辑中，逻辑算符反异或闸（英语：Exclusive NOR）是对两个运算元的一种逻辑分析类型，符号为XNOR或ENOR或 ⇔ 。

Answer 2

A direct translation of "if and only if" is "如果，只有如果", which doesn't express the intended meaning well in Chinese, at least it is not a common way we speak.

The function of "only" in this phrase is to stress the word 如果 (the important thing has to be said twice)

The better interpretation of "if and only if" is "如果，我说如果" (If, I said if")

• 如果，我说'如果' X = Y

• If, I said 'if' X = Y

• (only when X = Y, the following statement would be valid)

Answer 3

You can use “当且仅当”：当且仅当A成立，B成立。

Or you can say: B成立的充要条件是A成立。

The expressions above is widely used in textbooks in PRC.

以上的表述在中华人民共和国的课本中广泛使用。