gogul: Well, I for one am fond of coining such multiple contractions (we'll've, it'sn't, they'ven't, etc.) in casual writing, but I think you'lln't've much chance of finding them in a dictionary.

KotDB: I see. I'm just'bt to recover'n start again'o'se the ' in my writing and wondered where the limits are of the correct forms. Thanks.

KotDB:According to what I have learnt here in university, 'have' when used as a verb meaning to possess, cannot be contracted.  So basically the sentence "I've two cats at home." is wrong.  It is to be written in its full form when used as the main verb, but can be contracted when used as part of a verb like " I would've had to swim if I hadn't found my canoe."

King Reza: "Have" can be contracted even when used as the main verb; I think this is more common in the UK than in the USA. Here on the Web, Google finds no small number of instances of "I've a", "I've the", and "I've two cats".

Now the propriety of such usage is a separate question. Arguments over grammar often boil down to a question of "Says who?", and contractions are one of the murkier areas if you're looking for absolutely binding rules. It's true that they're best avoided in formal speech and writing, but otherwise if you want to contract, contract. I don't know of anyone with the authority to tell you you mayn't.