Split Infinity by Piers Anthony

their wall.
    Stile climbed into a crate. Sheen walked on, so as not to give his position away. She would try to mislead the pursuit. If this worked, they would be home free for a day, perhaps for the whole week. Stile made himself halfway comfortable, and peered out through a crack.
    No sooner had Sheen disappeared than a mech-mouse appeared. It twittered as it sniffed along, following their trail. It paused where Stile’s trail diverged from Sheen’s, confused, then proceeded on after her.
    Stile relaxed, but not completely. Couldn’t tell the difference between a robot and a man?   Sniffers were better than that! He should have taken some precaution to minimize or mask his personal smell, for it was a sure giveaway—
    Oh, Sheen had done that. She had given him a scented shower. The mouse was following the trail of rose—and Sheen’s scent was now the same as his. A living hound should have been able to distinguish the two, but in noses, as in brains, the artificial had not yet closed the gap. Fortunately.
    But soon that sniffer, or another like it, would return to trace the second trail, and would locate him. He would have to do something about that.
    Stile climbed out of his box, suffered a pang in one knee, ran to his original trail, followed it a few paces, and diverged to another collection of crates. Then back, and to a truck-loading platform, where he stopped and retreated. With luck, it would seem he had caught a ride on the vehicle. Then he looped about a few more times, and returned to his original crate. Let the sniffers solve that puzzle!
    But the sniffer did not return, and no one else came.   This tracking operation must have been set up on the simplistic assumption that as long as the sniffer was moving, it was tracking him. His break—perhaps.
    Time passed. The night advanced. Periodically the food machines exhausted a crate of cartons and ejected it, bumping the row along. Stile felt hungry again, but knew this was largely psychological; that double handful of regurgitated pudding should hold him a while yet.
    Where was Sheen? Was she afraid to return to him while the sniffer was tracking her? She would have to neutralize the mech-mouse. Far from here, to distract suspicion from his actual hiding place. He would have to wait.
    He watched anxiously. He dared not sleep or let down his guard until Sheen cleared him. He was dependent on her, and felt guilty about it. She was a nice .. .   person, and should not have to—
    A man walked down the hall. Stile froze—but this did not seem to be a pursuer. The man walked on.
    Stile blinked. The man was gone. Had Stile been nodding, and not seen the man depart—or was the stranger still near, having ducked behind a crate? In that case this could be a member of the pursuit squad.   A serious matter.
    Stile did not dare leave his crate now, for that would give away his position instantly. But if the stranger were of the squad, he would have a body-heat scope on a laser weapon. One beam through the crate—the murder would be anonymous, untraceable. There were criminals on Proton, cunning people who skulked about places like this, avoiding capture. Serfs whose tenure had expired, but who refused to be deported. The Citizens seldom made a concerted effort to eradicate them, perhaps because criminals had their uses on certain occasions. Such as this one? One more killing, conveniently unsolved, attributed to the nefarious criminal class—who never killed people against the wishes of Citizens. A tacit understanding. Why investigate the loss of an unemployed serf?
    Should he move—or remain still? This was like the preliminary grid of the Game. If the stranger were present, and if he were a killer, and if he had spotted Stile—then to remain here was to die. But if Stile moved, he was sure to betray his location, and might die anyway. His chances seemed best if he stayed.
    And—nothing happened. Time passed, and there was no further evidence of the man. So it