What do you call the following types of sentences?

[Bhikkhu1991a]

Hello,

What do you call the following types of sentences and when do you use them, please? Aren’t they called sentence fragments?

1. 'Window' I have used here to mean the chance to learn new ideas.
2. I’m sorry, I lost it.
3. Sorry, I don’t mean to hurt you.
4. Sorry! I don’t mean to hurt you.

I look forward to hearing from you, and thank you so much.

Best wishes,
Bhikkhu1991a.

[Mister Micawber]

The first three are normal sentences. #4 is composed of 2 sentences. I see no fragments; a fragment is a phrase or clause that cannot stand alone.
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Native English teacher at Mister Micawber's

[Bhikkhu1991a]

Hello Mister Micawber,

Thank you so much for your reply; as a result, I have understood the fourth sentence.

However, I still don’t understand the other three sentences. Isn’t the second sentence faulty? It’s made up of two clauses joined by a comma.

[Mister Micawber]

These are all very casual sentences where semicolons would be out of register. '(I'm) sorry' can be considered a commentary interjection in both 2 and 3. In #1, 'Window' is simply the object of the verb 'use'.
_________________
Native English teacher at Mister Micawber's

[Bhikkhu1991a]

Hello Mister Micawber,

Thank you for your prompt reply. I’m pleased to inform you that I’ve also understood the second and third sentences. Basically, they are mild interjections using commas instead of exclamation marks.

However, I’m still doubtful about the first sentence. Technically, is it called the “left dislocation” in the textbook? For example, a left dislocation has a comma preceding the clause—'Window', I have used here to mean the chance to learn new ideas.

I look forward to hearing from you. Thank you so much.

Best wishes,
Bhikkhu1991a.

[Mister Micawber]

No, it is not dislocation in that sense-- that happen with adverbs, for instance. Window is the object of the verb, and as such cannot be separated from its verb by a comma.

'Window' I have used here to mean the chance to learn new ideas = I have used 'Window' here to mean the chance to learn new ideas
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Native English teacher at Mister Micawber's

[Bhikkhu1991a]

Hello Mister Micawber,

Thank you so much for your help and patience. At last, I’ ve found the answer to the first sentence. It’s called PREPOSING technically, and PREPOSING is used in close connection with something that is previously mentioned. For instance, the first sentence is used by Mr. Alan Townend in the following excerpt.

[Mister Micawber]

You'll need a major comprehensive grammar book, I think, like Quirk, et al's Comprehensive Grammar of the English Language or Huddleston & Pullum's Cambridge Grammar of the English Language. I don't know of any online sources offhand.
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Native English teacher at Mister Micawber's

[Bhikkhu1991a]

Hello Mister Micawber,

Thank you so much for your recommendation about grammar books.
Bye for now!

Best wishes,
Bhikkhu1991a.