Qui est Film Noir?

So, after thinking about it for a long time, watching some of its variety, and talking about it in class, I think I may be able to come up with a list of certain things I think a noir film must have.
Here it is

1) Crime always seems to be the most important thing for film noir. By crime I mean any form or illegal activity. This by no means is just cop and robbers crime. In Double Indemnity it was killing and insurance fraud, and in The Set-Up it was the proposed act of throwing a fight aka rigging the game.
2) Low Lighting/Use of Darkness Pretty selfexplanatory. Most Noir films are dark in content, so most to nearly all of them are dark visually. I noticed how the shadow over the face seems to be very common.
3) C'est la vie. I think this is something that I started see in Blade Runner. I like to call it the "so it goes" idea (thank you Kurt Vonnegut). This could also be defined by the more commonly known French phrase, "C'est la vie." It is the idea that no matter what, at the end of the film, things go on. At the end of Touch of Evil, we see Tanya and Schwartz talking about the events. Just by the way they are talking, you can see a sense of "O, well." I imagine this as being a direct opposition of the beginning Depression era films were things work out in the end (like Casablanca) .

to be continued