Veo al maestro PK Veo a tu maestro
I got that 'a' is always there when refers to a person, but what about 'al'? Is it some kind of abbreviation for 'a' and 'el' (Im only guessing...)? Then what about 'a' and 'la' ?
Don't want to be nitpicking, just to be clear: Tilde: ~ like above the ñ in mañana. Acute accent: ´ like above the é in él. Great explanation about the contractions, anyway.
Edit: just checked, and according to Wikipedia Spanish is the exception, in which any accent mark may be called a 'tilde'.