This is annoying. One of the explanations in another discussion topic (sorry, I didn't take the reference) is the use of "dall'orso", where the man goes to the bear. The explanation is that the preposition changes if the subject is "a living being", in that case a bear, but surely this also applies in this case. Would someone please clarify the rules regarding the use of this preposition : The man goes to the bear - L'uomo va dall'orso The woman writes to the man - La donna scrive all'uomo. It may be they are interchangeable, I can accept that, but if there is a rule regarding changing the preposition, then either "to the bear" is wrong or "to the man" is wrong.
"Ad Anna" is correct ("d" is mandatory when the preposition ends with the same letter the noun begins with). "Al Anna" is incorrect, because "al" is "a" + "il", "il" being a masculine article that does not go well with a feminine person. "All'Anna" would be correct if we used definite articles with proper names. "A" + "l'" becomes 'all'"; l'uomo, therefore "all'uomo".