Permutation City

Carter said, 'I hope you don't mind if we keep this brief and to the point. I don't like to use inducers for more than twenty-four hours at a stretch.'

Peer said, 'It's good of you to make the time to see us at all.' He cursed himself silently; he was contemplating paying this man a substantial portion of his entire wealth -- and trusting him with the fate of an autonomous version of his own consciousness. He had a right to an audience. Still, at a slow-down of sixty . . .

Carter -- if it really was Carter, and not just a convincing mask -- pointed out a door at the end of the room. 'There's a rough sketch of the city through there, if you want to take the tour later on; just call out for a guide if you need one. But I expect the city itself's not your main concern. What you really want to know is, can I fit you safely into the cracks?'

Peer glanced at Kate. She remained silent. She was already convinced; this was all for his benefit.

Carter held out a hand toward the middle of the room. 'See that fountain?' A ten-meter-wide marble wedding cake, topped with a winged cherub wrestling a serpent, duly appeared. Water cascaded down from a gushing wound in the cherub's neck. Carter said, 'It's being computed by redundancies in the sketch of the city. I can extract the results, because I know exactly where to look for them -- but nobody else would have a hope in hell of picking them out.'

Peer walked up to the fountain. Even as he approached, he noticed that the spray was intangible; when he dipped his hand in the water around the base he felt nothing, and the motion he made with his fingers left the foaming surface unchanged. They were spying on the calculations, not interacting with them; the fountain was a closed system.

Carter said, 'In your case, of course, nobody will need to know the results. Except you -- and you'll know them because you'll be them.'

Peer replied, almost without thinking, 'Not me. My clone.'

'Whatever.' Carter clapped his hands, and a multicolored, three-dimensional lattice appeared, floating in the air above the fountain. 'This is a schematic of part of the software running the sketch of the city. Each cube represents a process. Packets of data -- those blips of colored light -- flow between them.

'There's nothing so crude as a subset of processes dedicated to the fountain. Every individual process -- and every individual packet of data -- is involved with some aspect of the city. But there are some slightly inefficient calculations going on here and there, and some 'redundant' pieces of information being exchanged.' Pin-pricks in a smattering of the cubes, and some of the data, glowed bright blue. 'One of the simplest tricks is to use a vector when only a direction is needed -- when the magnitude of the vector is irrelevant. Perfectly reasonable operations on the vector, entirely justified in their own context, incidentally perform arithmetic on the magnitude. But that's just one technique; there are dozens of others.' He clapped his hands again, and everything but the blue highlights vanished. The diagram re-formed, the scattered processes coming together into a compact grid. 'The point is, the fountain gets computed along with the city, without any of the software explicitly stealing time for a parasitic task. Every line of every program makes sense in terms of computing the city.'

Peer said, 'And if Durham runs your code through an optimizer which rescales all the unnecessary vectors, trims away all the inefficiencies . . . ?'

Carter shook his head. 'I don't believe he'd meddle with the code at all, but even if he does, optimizers can only track things so far. In the full version of the city, the results of your calculations will propagate so widely that it would take months for any program to deduce that the data's not actually needed somewhere -- that it ultimately makes no difference to the legitimate inhabitants.' He grinned. 'Optimizing anything to do with Copies is a subtle business. You must have heard about the billionaire recluse who wanted to run as fast as possible -- even though he never made contact with the outside world -- so he fed his own code into an optimizer. After analyzing it for a year, the optimizer reported this program will produce no output, and spat out the optimized version -- which did precisely nothing.'

Peer laughed, although he'd heard the joke before.

Carter said, 'The fact is, the city is so complex, there's so much going on, that even if it had all been left to chance, I wouldn't be surprised if there were some quite sophisticated secondary computations taking place, purely by accident. I haven't gone looking for them, though -- it would bum up far too much processor time. And the same applies to anyone searching for you. It's just not a practical proposition. Why would anyone spend millions of dollars scanning for something which can do no harm?'

Peer gazed up at the blue schematic skeptically. Carter came across as if he knew what he was talking about, but a few plausible-looking graphics proved nothing.

Carter seemed to read his mind. 'If you have any doubts, take a look at the software I used.' A large, fat book appeared, floating in front of Peer. 'This modifies program A to surreptitiously carry out program B, given A is sufficiently more algorithmically complex than B. What that means, exactly, is in the technical appendix. Try it out, show it to your favorite expert system . . . verify it any way you like.'

Peer took hold of the book, squeezed it down to credit-card size, and slipped it into the back pocket of his jeans. He said, 'There's no reason why you shouldn't be able to do everything you claim: piggyback us onto the city, hide us from searches, protect us from optimization. But . . . why? What do you get out of this? What you're asking for is nothing, compared to what Durham must be paying you. So why take the risk? Or do you screw all your clients as a matter of principle?'

Carter chose to seem amused, not offended. 'The practice of skimming off a percentage of a construction project has a long, honorable tradition. All the more honorable if the client's needs aren't seriously compromised. In this case, there's also some elegant programming involved -- worth doing for its own sake. As for the money, I'm charging you enough to cover my costs.' He exchanged a look with Kate -- for Peer's benefit, or he wouldn't have seen it. 'But in the end, I'm only making the offer as a favor. So if you think I'm going to cheat you, you're welcome to decline.'

Peer changed tack. 'What if Durham is cheating his clients? You're only screwing them out of a few QIPS -- but what if Durham doesn't plan to run the city at all, just vanish with the money? Have you ever seen his hardware? Have you used it?'

'No. But he never claimed -- to me -- that he had his own hardware. The version of the story I got is that the city's going to run on the public networks. That's bullshit, of course; the Copies funding him wouldn't wear that for a second -- it's just a polite way of telling me that the hardware is none of my business. And as for vanishing with the money, from what I can deduce about his cash flow, he'll be lucky to break even on the project. Which suggests to me that someone else entirely is handling the true financial arrangements; Durham is just a front man, and the real owner of the hardware will pay him for his troubles, once the whole thing is wrapped up.'

'The owner of what? This hypothetical 'breakthrough machine' that nobody's laid eyes on?'

'If he's persuaded Sanderson and Repetto to pay him, then you can be sure he's shown them something that he hasn't shown me.'

Peer was about to protest, but Carter's expression said: take it or leave it, believe what you like. I've done this much for my ex-lover, but the truth is, I don't care if you're convinced or not.

Carter excused himself. When he turned and walked away across the room, footsteps echoing in the cavernous space, Peer couldn't believe he would have hung around for the fifteen real-time minutes it took to reach the exit. Not a busy man like that. In fact, he'd probably conducted two or three other meetings with Copies while he'd been talking to them, dropping in and out of the conversation, leaving a mask to animate his features in his absence.

Kate said, 'What's the worst that can happen? If Durham is a con man, if the city's a hoax, what have we lost? All money can buy us is QIPS -- and you're the one who's so sure that it doesn't matter how slowly we run.'

Peer scowled, still staring at the exit Carter had used, surprised to find himself reluctant to drag his gaze away. The door meant nothing to him. He said, 'Half the charm of this lies in stealing a free ride. Or bribing Carter to steal it for us. There's not much . . . dignity in stowing away on a ship going nowhere.'

'You could choose not to care.'

'I don't want to do that. I don't pretend to be human, but I still have a . . . core personality. And I don't want equanimity. Equanimity is death.'

'On the skyscraper --'