"Lasciare" also means "to let", and "lasciar perdere" is an expression that means "to let go", but only in the sense of "let it go, forget about it, I don't care anymore". "Let him go (somewhere)" for example would be translated literally, "lascialo andare".
Instead of "lascia perdere" one can also say "lascia stare" ("leave it alone", "leave it be").
If I was more crafty I would make you a "superman" type logo'd shirt with DL (for DuoLingo) on it. You always come in and save the day, DuoFaber. Thank you very much for your easy-to-understand explanations. I have noticed that you seem to clear up many of these questions. I appreciate it.
The english phrase "I let it go" could be used in either past or present tense, but it is more commonly used in the past tense. And, given that Italian often uses present perfect tense where English would use past tense, I would think that "l'ho lasciato" should be acceptable here.
The Italian phrase "Io lo lascio perdere" is in the present/ future tense, so DL may not accept the present perfect (l'ho lasciato) if the programming only knows the English phrase to be in present tense.
I'm not a native Italian speaker, however, so if I'm wrong, someone please chime in. :)
"(Io) lo lascio andare" means "I'm letting him go (somewhere)". So it's correct, but it means something different :)
"Lascio perdere" is just an expression that means "I'm letting it go, I don't care anymore" (what's "it" in this case? usually a discussion, or something you were interested in just moments ago). It's more common to hear someone say that to someone else, "lascia perdere!" (or "lascia stare!", same thing), meaning "forget about it!", "leave it be!".
When referring to someone, "lascialo perdere" would mean something like "forget about him, don't give him any attention, it's not worth it", while "lascialo stare" would mean "leave him be, leave him alone". And again, "lascialo andare" would be translated literally as "let him go (somewhere)", or even "let him leave". I hope this explanation wasn't too confusing.
Lipofefeyt, English has a close idiom involving 'lose', namely 'get lost' which granted doesn't mean exactly the same thing, but it shows that words have multiple meanings, some literal, some figural. The idea in this one is, "I let it go' in the sense that if it gets lost, I don't care. Bottom line, don't expect literal, word for word equivalents when dealing w/ a foreign language and one's own.
Thanks for the explanation, but i must say you're wrong about you're assumption on me. In my native language (portuguese), in fact "lo lascio perdere" means "deixo-o perder-se", which stands exactly for "i let him get lost", so what you said.
Since i'm quite experienced with languages and i've been learning a lot of them over the years, i assumed that this would not be the case of a literal translation (because usually in english it is not), so i assumed the contrary. My assumption was wrong indeed, but no need to tell me that literal translations don't work mate.
Lipofefeyt: Sorry if you were offended, but I stand by my observation about literal translations -- they rarely work. In over 40 yrs of teaching German at the university level the students who never 'got it' were those too timid or stubborn to get away from the idea that they could open a dictionary and simply plug in one word after another for the original and come up with anything that made sense. The result was usually something that either made no sense whatsoever or simply sounded awkward. Of course simple straightforward sentences can be approached that way, but language is far too complex and idiomatic to do that effectively in the long run.