“……?!”
“Huh?!”
Ten-chan gasps and I can tell Keika is halfway to her knees.
Sometimes, when a player loses in an extremely frustrating way, they’ll surrender by scattering the pieces on their stand across the board. I bet that’s what they think I’m about to do.
―――Sorry for the confusion!!
Holding your pieces to keep your opponent from seeing them is bad manners. But right now …… for the one minute I have, I’m going to insist!
“…………”
I close my eyes.
A mental Shogi board appears and I visualize sticking my hand into it.
I know the pieces I have in my hand. I have to use them and what’s on the board to make a Shogi puzzle so hard that even a supercomputer can’t solve it right away.
―――I can do it! It’s the only way to win!!
I follow Chairman Tsukimitsu’s advice and think only in terms of Shogi puzzles. I’ve already got some of my own sequences in mind.
And, above all, my heart is dead set on finishing the puzzle no matter what!
“Here―――”
I squeeze the pieces as if sending up a prayer to the Shogi gods and bow my head.
My train of thought dives into the opposite side of the board.
When I concentrate as hard as I can, everything slows down. Outside noises sound muffled, like being underwater.
There is no one way to make Shogi puzzles and the time needed varies from person to person.
Some creators say puzzle themes come to them in their dreams while others think and think and think about one specific theme until the puzzle completes itself.
But there’s an obvious pattern that all puzzles made by Shogi players have in common.
―――A heavy reliance on reading.
Efficient and precise late-game skills are necessary to win at Shogi. The ability to manage overwhelming amounts of information in the late-game is literally what brings home the bacon for Shogi professionals. They couldn’t survive in this competitive world without it.
That’s why puzzles made by Shogi players are easy to solve for Shogi players. It’s their weak point.
―――That won’t work! Ten-chan will figure that out right away.
I’m picturing a puzzle that challenges the reader to think.
One that finishes by breaking the rules with a Pawn Drop Mate after thinking through it all the way to the end …… But the key to avoiding it is in the first few moves. A puzzle like that.
My mind delves even deeper …… Memories flash before my eyes, but going in reverse so I can find Awaji’s weak spot.
The first memory was from a few days ago.
“There’s no weak spot. It’s built,” Master’s older brother told me after analyzing the data Futatsuzuka 4-dan gave me.
He threw his hands in the air and crushed any hope I had left. Agghhh ……
“Whew, I have to tell you, deep learning software has become a juggernaut. My LOLI is as good as dead. Deep learning is the name of the game now. LOLI is over and done.”
Agghhh ……
“So yeah, no weak spot. But―――”
“But?”
“You make your own Shogi puzzle, right, Miss Ai?”
“Um …… Yes. Master forbade me, but when he wasn’t around ……”
“Have you ever noticed software has trouble analyzing multiple check paths at once?”
“Yes!!”
That came out louder than I meant, but what he said happens quite a lot.
Everyone always says software is strong in the late-game and it never makes mistakes, so no one believed me when I asked them about this.
“But …… I thought that was because my computer wasn’t good enough.”
“It’s more of a program problem, actually. The process computers use to read sequences is surprisingly simple. First, they scan their memory for similar check path formations seen in previous matches and then find the shortest sequence to reach it.”
“How short?”
“5-move checkmates, usually.”
What?!
Only five? I mean …… I can read formations with check paths longer than that.
“The analysis that came out with Awaji’s match records made no mention of a checkmate routine. Personally, I think that’s because Awaji’s programming was originally designed for Go and then modified for Shogi. It’s lost that element.”
“What does that mean?”
“Awaji is strong, but it underestimates Shogi.”
Master’s older brother uses chess software as an example.
“Pieces steadily decrease during a chess match, so analysis of the end-game is over and done. Chess software will announce mate once it detects a seven-move check path.”
“Does that mean it has every possible seven-move check path memorized?!”
“Yes. The chess version of Shogi puzzles can’t use orthodox themes anymore. A variant called Fairy, which uses special rules is mainstream now.”
I-I had no idea ……
But Shogi hasn’t reached that point.
“Two special rules: taken pieces can be redeployed and forbidding Pawn Drop Mate, create a vast world within Shogi that sets it apart from other board games. In fact, Shogi’s late-game can be considered a completely different game on its own.”
A different ……. game ……
“People changed the rules of Shogi to make Shogi puzzles more interesting. That’s the defining factor that makes the game called Shogi so different. Two separate realms are contained within a single board. Nothing else in existence does that.”
“! That’s what ……”
I’ve heard something just like that before.
It was during Master’s first defense of the Ryuo title. On the airplane to Hawaii, we were talking about how the Meijin once said, “The offense would always win if it weren’t for Drop Pawn Mate.”
Master said, “I think that was just added to make Shogi puzzles more interesting.”
Maybe Master and his brother reached that conclusion together?
“Computers can’t read what the author of a particularly difficult Shogi puzzle had in mind. There is no other way for them to be 100 percent accurate than to flat out read the formations, like 5-move checkmates. Depending on the puzzle, however, all that reading could take a lot more than a minute.”
“Even for a supercomputer?”
“Yeah. The faster they read, the more formations they have to store in their memory. It’s only a matter of time before that memory gets overloaded.”
“What happens then?”
“In my software’s case, it tried to promote a Rook where that wasn’t possible, which is against the rules. Basically, it glitched.”
“That can ……”
“I’m not sure about deep learning software like Awaji’s, but there’s a possibility something similar will happen.”
Master’s older brother went on to guess that, unless the creator was extremely particular about Shogi puzzles, no one would bother fixing that bug.
Since Awaji’s Shogi solution was based on data with this flaw still in place, there could be a small hole in the armor.
“In Shogi, more options are available when more pieces are on the piece stand rather than on the board …… Which, in turn, makes reading what’s there much more difficult in the late-game. And, by outlawing consecutive Check Repetition Draws and Pawn Drop Mate, interactions between the number of pieces on the stand and unpromoted pieces on the board become even more complex.”
“I know of a few Shogi puzzles based on that, but in actual matches―――”
“The odds of a difficult check path like that showing up are tens of thousands to one. That’s not even a margin for error. Developers think so, too. All we’re interested in is improving our win rate. But players aren’t like that, now are they?”
“Right, because competitors know that winning this match could change their life ……”
I’m starting to understand what he’s trying to say.
“Two players go against each other. One wants to win as much as possible and the other thinks I only have to win this match. In other words―――”
“Yes?”
My heart pounds as I wait for his next words.
“You have a chance to beat Awaji, Miss Ai.”
“……!!”
“Even machines can’t beat you when it comes to making Shogi puzzles. If you can’t read to a checkmate in the late-game, neither could a supercomputer. At least not in less than a minute, it couldn’t.”
“So I need to make the late-game look like a Shogi puzzle ……?”
―――That’s impossible! common sense shouted at me.
But someone in an even deeper place whispered to me.
They said that if I could fully concentrate, the chances weren’t zero.
“Computers …… What kind of problems give them trouble?”
“Problems where there are many ways to put the King in check no matter how they respond on top of implicitly showing several sequences to read, which hides the true intention of the creator, I believe.”
“…………”
“By the way, the 1,525-move solution to Microcosmos is easy enough to figure out. The length has nothing to do with it.”
Even I understood that.
Microcosmos is extremely long, but there are only so many ways to put a King in check. As a problem, it’s not all that hard. It was designed to be long, so lack of difficulty doesn’t take away from its value as a Shogi puzzle.
“Ah ………… Could I show you something? I have it right here―――”
Shogi Suizou.
The collection of unpublished Shogi puzzles Kugui-sensei gave to me.
One of them matched Master’s older brother’s description to a “t.”
“This puzzle here. Number 17.”
“Hm? ………… How about that? It’s designed so only the Lance can block, right?”
Only a decorated amateur like Master’s older brother could have identified the theme that quickly.
Once he had time to read deeper ……
“O-Oh wow …………?!”
His eyes fly open in surprise. I admit it was satisfying to watch.
I remember blurting out “No way?!” back when I first figured it out.
“It’s a 67-move sequence …… But out of all the puzzles I know, I think this would take the longest to solve if you couldn’t identify the theme.”
“And since it hasn’t been published, this puzzle won’t be in any software’s database! Yeah, this just might work.”
He took a picture of the page in Shogi Suizo with his phone.
“I’ll run it through the computer right now. Let’s see how many minutes it takes ……”
I sent up another prayer to the Shogi gods as Master’s older brother walked away.
To please, please, please take more than a minute ……!
I don’t think I stopped praying while I waited for him to message me. He never did that day, which actually gave me more hope.