Definite article before acronyms [duplicate]

Sadly What I learned from [...] was that whenever we use (specific) acronyms, we don't use 'the' when they are within a sentence, and we use 'the' when a sentence starts with them indicates rather more about his use of it, than about English.

Is it not wholly irrelevant whether the acronym starts or is within a sentence? If the full-out phrase, in this case the Hamiltonian Cycle Problem needs an article then so does the abbreviation… except where the author can demonstrate how that article is included in the abbreviation.

(i) The HCP… seems correct by itself; is an NP-Complete problem contributes nothing.

(ii) … to solve HCP seems to be lacking an article, whichever that be. Please consider a rather different example of MP meaning Member of Parliament.

The crucial point here is that Joe Soap, who is MP works only in a very few, very specific circumstances; otherwise it fails solely because it has no article.

Joe Soap, who is MP for Piddlington does work in both abbreviated and full forms.

Joe Soap, who is the MP for Piddlington does work in both abbreviated and full forms.

Joe Soap, who is an MP does work - even though using an for the abbreviation almost contradicts the ordinary use of a for the full version.

Joe Soap, who is a MP doesn’t work in abbreviation even tough it should work with the full form, Member of Parliament.