I'm only familiar with how deprecation works in Gernany, but here, deducting that 10,000$ printer in one go would not fly. Since the reduced profit would also reduce your tax burden.
Saledovil
Well, if Grace is already well known, then her public key should be available.
Bob would have to know and trust Grace beforehand. Grace could be the IRS, for example. The idea here being to have somebody who already knows your age vouch for your age.
We could just make the middle man somebody who already needs that information, e.g. the IRS.
Here's my idea: Bob gives Alice a token, assigning her an unique random number n. Alice goes to Grace and tells her, "Somebody assigned me number n, can you verify that I'm allowed?" Grace then writes: "User n is allowed, signed Grace". Alice then takes this letter and shows it to Bob. Bob now knows that Alice is allowed, but nothing else. Grace only knows that somebody wanted to know that Alice is allowed, not who that somebody is.
Of note here: This system does nothing to protect against an allowed user helping a not allowed user to gain access, but I don't think it's possible to protect against traitorous users.
Same way you short anything else, you borrow it, sell it, and then buy it back once the price has dropped, and return it.
Investors could be bailed out. As in you invested 10e11$, so now the government gives you that money back.
What does PI mean (first sentence of your post)?
Really good ability to locate the source of a sound.
A potential strategy could be attacking Democrat seats. If a pressure group can show that they can oust a Democrat, they should be able to use that threat to influence others.
Eh, that could also include sales revenue, of which Valve pays out 70% to right holders.
Yeah, that is a problem.
And thanks for the compliment.