comma after 'however' / 'then' [adverb, front position]: However, not

[uktous]

hi,

(Have comma)
Some of us want a new system. However, not everybody agrees

(No comma)
I worked until 5:00. Then I went to home.

The above 2 sentences are found in a book.

Is there any rule that we should write a comma after the adverb that goes in front position?

Any difference in term of meaning and grammar between the above and the following sentence?

(No comma)
Some of us want a new system. However not everybody agrees

(Have comma)
I worked until 5:00. Then, I went to home.

thanks

 

[EnchiladaJack]

The comma is optional for "then," "so," and "yet." Pretty much all other adverbial introductions (e.g. "however," "therefore") need the comma.

 

[timpeac]

hi,

(Have comma)
Some of us want a new system. However, not everybody agrees

(No comma)
I worked until 5:00. Then I went to home.

The above 2 sentences are found in a book.

Is there any rule that we should write a comma after the adverb that goes in front position?

Any difference in term of meaning and grammar between the above and the following sentence?

(No comma)
Some of us want a new system. However not everybody agrees

(Have comma)
I worked until 5:00. Then, I went to home.

thanks

A very rough "rule of thumb" for commas is to judge if they add something. I tend to view them as brackets () in maths. What remains within them has to make sense in and of itself.

In your two examples I agree with your textbook. In the first you could say simply "not everybody agrees" without the "however" - it is extra. Therefore there is a comma. In the second you cannot have a comma because "I worked until 5. I went home" makes no sense. The "then" is vital to the meaning of the second sentence and can't be split from it.