THE APOSTOLIC CAFé had expanded its offerings to include Euclid’s Grill—casual buffet by day, fine dining by night, served in the former nave. Tristan and I went directly there from the airport that evening. Waiting for us were Frank, Rebecca, Erszebet, and the newest member of our little band, Mortimer Shore. Mortimer was the historical swordfighter whom Rebecca had recruited from the park, and who had trained Tristan in the use of the backsword. He was a tall, rangy Californian with a mop of wavy dark hair and a bushy beard that as often as not framed an easy smile. He was double-majoring in metallurgy and computer science at MIT, but Tristan had talked him into putting his academic career on hold so that he could go full-time as DODO’s systems administrator and in-house swordfighting expert. These four had already grabbed the big booth in the corner of the restaurant, reserved under the name of the East House Trust. Resting in an ice bucket nearby was a magnum of champagne that looked expensive. To judge from the high fives and hugs with which they greeted us (yes, even from Rebecca), they were already well into it. We hadn’t told them the weird story about Frederick yet, and it wasn’t clear that we needed to.
Julie the Smart-ass Oboist (who always seemed to be our waitress) uncorked the magnum and came to our table to pour flutes of champagne for Tristan and me, and we went through several rounds of toasts. Erszebet, looking like she’d been born with a glass of bubbly in her perfectly manicured hand, was determined to teach everyone how to toast properly, in the traditional European style: you had to look each person straight in the eye as you clinked glasses with them. She was looking more cheerful than I’d have expected, given that her precious számológép was still locked up in some vault in the Trapezoid. I said as much to her. She allowed as how she was so very (grudgingly) chuffed by the success of the venture, and her role in it, that she had decided to delay her relocation to Hungary until we were able to replace her, by bringing forward through time more witches to work in the ODEC.
Tristan got to the bottom of his champagne glass pretty quickly. He still had a haunted look about him, as if he’d seen a ghost in Central Park. Not really the champagne type, he raised one hand and hailed the Smart-ass Oboist.
“What can I get you?” Julie asked.
“The usual,” he said, his attention already on the dinner menu.
She faltered, her face pinkening slightly. “I’m sorry,” she said. “I feel like I should know what that is, but the memory escapes me . . .”
“Old Tearsheet Best Bitter!” he said, glancing up.
She frowned. “I don’t think we have that,” she said. “Is it an import?”
He gave her an Eagle Scout smile, but his tone was firm. “You know. I’ve been ordering it since this place opened. You definitely carry it.”
“All right,” she said with a skeptical smile, writing. “T-e-a-r-s-h-e-e-t? Bitter?”
“That’s right,” said Tristan.
We all perused the menu, until she returned a moment later with the announcement that they did not carry—and had never carried—Old Tearsheet Best Bitter. Tristan half stood up and looked incredulously over at the barman, who shrugged broadly, indicating he had never heard of that ale. That ale he’d been pouring Tristan for years.
Erszebet tugged at Tristan’s sleeve, pulling him back down into his seat. “This is the Diachronic Shear,” she said quietly. “There is no Tearsheet Brewery. After September of 1601, there never was.”
“That’s almost as big a tragedy as losing Les Holgate,” Tristan muttered under his breath.
IT WAS ODDLY intimate yet oddly formal, the six of us sitting around a proper dining table that was not littered with coffee cups, whiteboard markers, handheld devices, and notepads. That we were holding actual silverware, and napkins larger than a coaster. That we allowed a stranger to approach us and do something exquisitely mundane: serve us a meal that was not delivered in to-go containers or rewarmed in a microwave. That we ate slowly, savoring our food and relaxing in the hum of conversation around us, and feeling a part of the human race—or at least, that fraction of the human race that frequented the Apostolic Café.
As we ate, we reviewed our lessons learned about the use of time travel, all of which Erszebet felt the need to point out she was already aware of.
“Very well,” said Tristan, setting down his fork. “If you know everything, save us the time and aggravation and tell us what we don’t know yet.”
She made a tch’ing sound and shook her head. It is fair to say her condescension toward him was softening now—a little—into something more resembling big-sister exasperation. “What you do not know is almost everything. Quite literally. Except what my számológép could anticipate on any given Strand.”
“Clearly we’re still in the learning process there,” said Tristan. “We need to think in a little more depth about how to master the Strands.”
“You cannot master the Strands,” said Erszebet. “It is like a doctor with medicine. You can only practice. And you cannot do even that without the számológép.”
“It does seem to me there are discernible algorithms regarding the Strands,” said Frank Oda. He touched his wife’s wrist gently and she reached down to the floor for a bookbag, which she raised and handed to him.
“There is always, what is the term, wiggling room,” corrected Erszebet.
“It is a complexity theory problem—a branch of what mathematicians call graph theory,” said the professor.
“Graph? As in graph paper?” I asked.
“Math geeks use the term differently,” Oda said, “to mean structures of nodes connected by branches. Like a számológép, or Gráinne’s broom, or Rebecca’s heirloom.”
“Or the many forking Strands of history,” Rebecca said.
“Point being, a lot of progress has been made in recent decades around just these sorts of problems,” Oda said. Anticipating an objection from Erszebet, he added, “Which isn’t to say there’s no more ‘wiggling room,’ but we can tackle these questions now with well-tested algorithms, and graphical UIs.” He opened his bag and reached inside.
“We are better than any other humans at extrapolating from what the Strands tell us.”
“That’s true,” said Oda. From the bookbag, he withdrew an iPad. Rebecca took the bag from his lap and returned it to the floor as he set the iPad on the table before him. “However, computers can enhance and sharpen the abilities you already have. With all respect, even witches can benefit from an app.”
Erszebet looked at the iPad. “What is this?”
“It’s a present,” said Frank Oda. “I would not insult your history with the missing számológép by calling this a replacement számológép, so let us say it is your quipu.”
“That is a computer,” she argued. “It is a piece of machinery. It does not even have moving parts.”
Oda smiled at her, undisturbed by her attitude. “I took the premise of the quipu, and what you had shown me of your számológép, and I designed a program to do algorithmically what you do intuitively. Plus a graphical user interface to go with it!” He held up the iPad so that everyone could see it. On the screen was a branching diagram that might best be described as a mathematician’s attempt to reproduce the structure of those devices used by the witches. Call it a quipu, a broom, or a számológép if you will; they all had the same many-branched structure, and so did the thing that Oda-sensei had rendered on this screen. It was a constellation of small gleaming figures in various shapes and colors, like a Christmas tree; the structure that held it together was a snarl of fine colored lines. He dragged his finger on the glass, and the thing rotated around, showing that it was three-dimensional; he swiped, he zoomed, he tapped, and things happened. “It’s a work in progress,” he said shyly, “but with time and resources, we should be able to build it out.”
Erszebet looked profoundly insulted. “You are saying you can replace me with a machine?”