In normal speech I often say 'am' when I really mean 'I'm' or 'I am'. Unfortunately I can't think of an example now I've asked the question, but there are times when the sentence only sounds correct if I use 'am'. I'm not even sure I mean it as an abbreviation of I'm/I am.
Am is the first person singular present tense version of is. That's why it's only paired with I. I don't know if there would be any cases where it would be appropriate if I was not present, especially when there are so many other words that mean the same thing for different situations: is, are, was, were. I don't think it would be grammatically correct to use it without I since then you are lacking the noun that it goes with. Though it probably won't be too confusing since the noun would be implied, but it would seem informal. For example if I said, "Am heading to the store, do ya want anything?" the listener would know that I was the one heading to the store, but it'd be more proper to say I'm instead. Mind you, I'm not an expert on grammar so I may be way off here, but this is my understanding.
I think that's what I mean, but if I were writing that sentence I wouldn't use 'am', I'd use 'I am' or 'I'm' so it's not a good example of what I mean. All I can tell you is that there instances where the sentence only sounds correct if I use 'am'. The most annoying thing is I wrote a reddit post where I used 'am', and it prompted this post. Now I can't find the sentence.
I don't know what you just said to me. You need to speak like you're talking to a five-year old for me to understand.
It's just a form of the "to be" verb. Like "are" and "were" and "is." You'd never see it without "I" except in colloquial speech where "I" is dropped.
It's a word, the form of "to be" that goes with "I" (1st person, indicative). What may be in play is elision, and elision points are different in different regions of a language. For example: "David said he'd call, but he never!" You won't hear that particular elision point in the USA, and even in the UK, it's particular to a certain group (looking at you, Vicky Pollard). In the U.S., that sentence is broken with the "did" at the tail end, and even that is still a kind of elision because the understood complete sentence is: "David said he'd call, but he never did [call]." Or when a Brit says: "Where's David?" "Down a pub." It's understood that the sentence has been shortened (elision) and that the complete, formal sentence is: Down at the pub. I feel that your particular example is a starting rather than an ending elision. You've come to the point where you're so comfortable dropping off the pronoun ("I") that it feels strange to add it.
Came back to add: I can, in fact, think of an example in AmE where I would use "am" the way you propose, but it's highly idiomatic. Tina looked at my screen and gasped. "You're... you're not doing what I think you're doing." "Am so," I replied without taking my eyes from the screen. That would work and be perfectly understood, but "am" in that sentence is not a different word to the "am" of "I am". It's just missing the "I".
I can't think of any instances where it would be grammatically correct to use it without "I" present. It's often used that way when speaking though (i.e., omitting the "I"). Am I sure? Maybe I am, or maybe I am not. I'll get back to you in the A.M.
"I'm not touching you!" "Are so!" "Am not!" "Yuh-huh!" "Nuh-uh!" Heard in a Trans-Am, running alongside the AmTrack.
My experience as a Brit (here in the North West at least) is we just say "Down Pub" or "Down the Pub". Go a little further, up into Yorkshire, and I've heard "Down't Pub".
Yes, okay, it's "the", but let's not get lost in the minutiae. The point is curtailment of syntax and the way that curtailment can lead one to feel that the short version is now the correct version.
It depends what of... and where you are in the country... cheap lager in spoons could be £2.50 , but if you want one of those pretentious real ales from a free house you won't see much change out a fiver