Is there a way to express the verb 'must' such that it means the subject does not have to do something? See:

I must go. -- I have to go.
I must not go. -- I have to avoid going.

I can't think of any 'must' equivalent to "I do not have to go". Is it conventional to use 'must not' here?

Yes. I must not go is a conventional sentence.

Yes, but that seems to say that I must avoid going, whereas what I want to say is that I do not have to go, or that it is not true that I must go, not in so many words.

"I must not go" implies that you shouldn't go.

Other examples:

I must not eat chocolate or I'll gain weight.

I must not eat peanuts because I'm terribly allergic to them.

If "I must not" isn't exactly what you mean, then you can use other words such as "I don't have to go."

Okay, thanks. I just wanted to make sure there wasn't a possible use of 'must' I was overlooking that would allow me to express "I don't have to" using 'must'.

You're welcome.

To express the meaning of "not having to do something" using the verb 'must,' it is not conventional to use the phrase 'must not.' Instead, you can use phrases like "do not have to" or "do not need to" to convey the meaning.

Here's how you can express the sentence "I do not have to go" without using 'must':

"I do not have to go." - This sentence implies that you have the choice or option not to go, but you are not obligated or required to do so.

To arrive at this phrase, you can start by understanding that 'must' typically indicates an obligation or requirement. To convey the opposite meaning, you can consider alternatives such as 'do not have to' or 'do not need to.'

If you encounter a situation where 'must not' is used, it expresses prohibition or the necessity to avoid a particular action. For example, "I must not go" means "I am prohibited from going" or "I need to avoid going."

In summary, to express the idea of not having to do something, it is common to use phrases like 'do not have to' or 'do not need to,' rather than 'must not.' However, context is crucial in interpreting the intended meaning, so it's essential to pay attention to the specific usage and implications of different expressions.