For centuries, there had been a law in cybernetic research: “For any program, there is a system such that the program cannot not know its system.” That is, a program, however complicated, even a human mentality, could not always be aware of the system it was running on, if no clues were provided by that system; it could only know the extent to which the system allowed it to run.

But less than a century ago, Hexamon investigators headed by a brilliant team-leader, homorph Doria Fer Taylor, had found mathematical algorithms which allowed programs to completely determine the nature of their systems. Thus, a downloaded mentality could tell whether or not it had been downloaded; Olmy could, in theory, know under any circumstances whether his focus of personality was running in implants or in his organic mind.

In theory, such algorithms, fully developed, could allow a mentality or program to change the nature of its system, to the extent that a system could be changed. Because of the existence of rogues in city memory, such information could have had disastrous consequences. The rogues—even one rogue—could have destroyed city memory and all that was in it. Human mentalities were not disciplined enough to be given such power. The researches had been classified. Olmy had learned of them through his police work, when he had been ordered by the presiding minister to investigate whether any mentalities in remote gate memories—human or otherwise—had independently discovered such power. None had.

Olmy searched his deepest levels of implant memory for the Taylor algorithms. He had often tucked away such items, trusting himself to keep them secure, unable to resist the chance to incorporate them into his personal data file. They were still available. He would have to purge them before—if—he ever downloaded into the current city memory.

Not likely, he thought.

Judging from what had happened to Beni and Mar Kellen, as well as the early researchers, the Jart mentality was aware of and fully capable of using the Taylor algorithms. But at the time of its capture, humans had not even known of their existence.

The Jart mentality, still an unknown quantity, had been removed to complete isolation in the fifth chamber, to be studied now and then across some number of decades, apparently less than a century, and then to be forgotten, but for an occasional inquiry as to status. Too valuable to be destroyed, too dangerous to be investigated…

The investigators had apparently all passed into city memory in their allotted times. Most had been Geshels. Equally apparent, all of them had chosen to go down the Way during the Sundering. That could explain why there had been no further inquiries in the last forty years; it did not explain twelve years of silence before that.

He called up the complete list of data and looked at the file access dates. Why check on static files if not to see whether somebody else has accessed them?