“I believe you have a valid concern,” Mandelbrot said.

Adam left his chair to stand beside Mandelbrot. “I agree. Our duty to intelligent beings everywhere demands that we find out whether the cities will destroy diversity, and whether that diversity is as important as you think it might be.”

Lucius-still wearing Derec ‘ s features-nodded. He rose to stand beside Mandelbrot and Adam, saying, “Thank you, Ariel. You have found a way for us to serve all of humanity in its many forms. “

Eve stood and joined the others. Ariel couldn’t suppress a giggle at the image of four robots presenting a united front against a galaxy-wide menace. But right behind the giggle came the shudder as she considered the menace itself. Maybe they were jumping at shadows, but then again, maybe they weren’t.

“All right,” she said, “let’s figure out what we’re going to do. I think our first priority should be to find Avery and keep him from spreading this around any more than he has already, at least until we know how dangerous it is.”

“Agreed,” the robots said in unison.

“All right, then, let’s get to it.”

“Derec?”

He looked up from the monitor, puzzled. Had someone spoken? He turned to see Ariel standing in the doorway, a worried expression on her face.

“Hi. Sorry to bother you, but…do you know where your dad is?”

Her words made no sense to him. Variables still danced before his eyes, those peculiar variable-variables that changed their meaning over time. Using those super-variables was the only way he could make any sense of the equation he’d copied by hand from his desktop, but even with the computer to keep track of their mutations for him, he could barely follow the concept in his mind.

At last a little of what Ariel had said percolated through. “Dad,” he said stupidly. “You mean Avery?”

Ariel frowned. “Of course I mean Avery. Who else? Do you know where he is?”

He tried to think. Avery. Where was Avery? Did he know? “Uh…no. No, I don’t.”

“It’s kind of important.”

“I still don’t know.”

“Some help you are.”

The sting behind her words helped jolt him out of his stupor. “Sorry. I…I do have a program trying to track him down, but so far it hasn’t found any sign of him.”

That mollified her a bit. “Oh. Well, if it does, let me know, okay?”

“Okay.”

She stepped farther into the room, looked over his shoulder. “What are you working on, anyway?”

“The formula. “

“What formula?”

“The one on my desk. It came back, and I had time to copy it this time. I think it’s a robotics formula, but I’m not sure.”

“You’re not even sure of that?”

“No. The meaning of the variables keeps changing.”

“Hmm.” Ariel gave him a quick kiss on the cheek. “Well, good luck. But remember to call me if you hear anything about Avery, okay?”

“I’ll do it.”

“Good.” Ariel left the room. Derec heard her say something to someone in the living room, then the apartment door opened and closed and there was silence. He turned back to the monitor and the formula.

It was both a formula and a program; he had discovered that much about it. It was a formula in that it definitely expressed a relationship between its various symbols, but it was a program in that it was dynamic, changing over time. He had even managed to run a portion of it with his computer in local mode, but since he didn’t know what input to give it, it had crashed within seconds.

For at least the hundredth time, he wondered if he was right about its origin. Had his mother sent it to him? Usually programmers would insert their names in the code somewhere to identify it as theirs, but Derec hadn’t found any section of non-changing code big enough to hold a pair of initials, much less a name.

Formula or program, the notation was incredibly dense. The whole thing fit into one screen full of code. He stared at it, as if waiting for it to suddenly resolve into something. Idly, knowing it would do no good, he pressed the incremental execution button, running the program one step at a time while he watched the code”. Different variables blinked with new values at each step, but they were never the same variables and never the same values.

Except one. He pushed the increment button again. Sure enough, one variable near the top left comer of the screen changed with each iteration. It was an alphabetic variable rather than a numeric one; he watched it through half a dozen steps as it changed: S-T-A-S-I-blank. Hmmm. It had disappeared entirely. He kept pushing the button and it appeared again: J-A-N-E-T-blank-A-N-A-S-T-A-S-I-blank-blank-J-A-N-ET-blank-A-N-A-S-T-A-S-I-blank-blank-J-A-N-E-T-blank…

“Of course!” he shouted. Why use over a dozen bytes of code when a single super-variable would do? He pushed the button again and again. ANASTASI. JANET ANASTASI. His mother’s name was Janet Anastasi.

“Well, Basalom, that didn’t take him long.”

Janet leaned back in her chair and smiled. Her son was a pretty good detective. She idly considered calling him directly and congratulating him, but after a moment’s thought she decided to let him finish what he’d started. At this rate it wouldn’t take him long anyway.

Sometimes Basalom seemed to be telepathic. He stepped out of his niche in the wall beside her desk and said, “I am confused. Why are you waiting for him to find you, when it is apparent that you wish to speak with him directly?”

Janet shrugged. “That’s just the way I want it to be.”

“Is it perhaps a manifestation of guilt?” the robot asked. “You have ignored him for so long, you cannot bring yourself to change that behavior now?”

“No,” Janet said immediately, but right behind it she felt the hot blush of shame. A bit too quick with the denial, wasn’t she? “All right, maybe so. Maybe I do feel guilty about it. But to just call him up now and expect everything to be all right would be absurd. If I let him find me, then it’s his project. He can decide how he wants it to be.”

“But you are intentionally leading him to you. Isn’t that functionally equivalent to calling him?”

“He can ignore the clues if he wants.”

Basalom remained silent for a moment before asking, “Did you plan it this way all along, or did this explanation come after the fact?”

“Beg your pardon?”

“I am trying to ascertain whether you originally intended to assuage your guilt in this manner, or whether it was a subconscious decision which you have only now stated in definite terms. “

“Why?”

“Because I am curious.” Janet laughed. “ And I’ve got only myself to blame for that. All right. Since you asked, I guess I decided subconsciously to do it this way. It just seemed the best way to go about it. I didn’t think about guilt or any of that; I just did it. Satisfied?”

“For now. Subjective matters are difficult to resolve, but I will try to assimilate the information into my world-view.” Basalom stepped back into his niche.

The indignity of it all. Psychoanalyzed by her valet. If she hadn’t made him herself, she would have sent him back to his manufacturer. But he was actually pretty perceptive when it came right down to it. She probably was trying to avoid the guilt of abandoning Derec. If she went to him she would have to apologize, or at least explain, but if he came to her she could maintain her reserve.

She suddenly wondered how long this subconscious arranging of events had been going on. Had she left her robots in Derec’s path on purpose, hoping they would eventually lead him to her?

No. Impossible. If anything, he had found them and kept them near him to lure her to him.

Another possibility occurred to her. By the look of things, Derec had been following Wendell around; what if Wendell were the one keeping the robots by his side in order to lure Janet back to him?