explain xkcd - User contributions [en]

Talk:3020: Infinite Armada Chess

2024-12-05T16:21:32Z

172.69.33.252: /* Hit me up when this becomes real. */ Certain draw?

Did I do well? Added a very very basic explanation. [[Special:Contributions/172.68.147.132|172.68.147.132]] 04:25, 5 December 2024 (UTC)

Well, yes but I wonder if just one tiny fix is needed. If you replace the white side with a simplyfied artillery tower, you reinvented space invaders.{{unsigned ip|172.71.160.70|04:57, 5 December 2024 (UTC)}}

I was personally hoping for an explanation of the Infinite Armada thing, and I feel like a link to the TV Tropes page doesn't really. Explain that at all. So I would love a bit of an expansion on that part! Just want to be sure I didn't miss some reference or something. [[Special:Contributions/172.68.23.91|172.68.23.91]] 05:48, 5 December 2024 (UTC)
: Likewise. I get the comic, but I assumed the 'armada' part was a reference that I just did not get. But it seems it is just a word choice. [[Special:Contributions/172.71.102.105|172.71.102.105]] 09:39, 5 December 2024 (UTC)

I think that since the error was "out of bounds", not "out of memory", it's referring to indexing outside of the region of memory that the program allocated to deal with the board. This would happen since instead of addressing rank 1..8, you could address rank 9, 10, 0, or -1. Unless bounds checking is performed when converting the board coordinates into linear array indices, you'd get an out-of-bounds error (or worse, succeed in reading or modifying memory that you weren't intending to). --[[Special:Contributions/172.71.30.253|172.71.30.253]] 05:45, 5 December 2024 (UTC)
:It was "Out of Bounds memory access". That means it was trying to access a memory address that was out of the bounds of the computer, as if it were trying to access the ω-th index of the board array, which would put it out of the memory range of any computer [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you want to]] | [[Special:Contributions/Firestar233|what i have done]]) 06:15, 5 December 2024 (UTC)
:: There is no hint that the bounds are those of the computer, the simplest explanation really is that the bounds are those of an array. The error message does come up. In addition, to try to access the memory at the ω-th index, you would need to construct the ω-th index itself first (which would fail or not terminate) [[User:Jmm|Jmm]] ([[User talk:Jmm|talk]]) 07:01, 5 December 2024 (UTC)
::: The specific message, "RuntimeError: Out of bounds memory access", is a WebGL error issuing from its WASM cross-platform browser implementation. This implies to me that an attempt to render an infinite chessboard failed in a fairly trivial way, because of a poor implementation. It's very unlikely that there had been a problem with the [https://github.com/official-stockfish/Stockfish/tree/master/src Stockfish playing algorithm] yet, which would have failed with a different message if it ran out of memory, such as "Killed", which is all that shells like Bash print when one of their job processes is killed by the kernel's OOM killer, or by anything else for that matter. [[Special:Contributions/172.70.215.21|172.70.215.21]] 12:58, 5 December 2024 (UTC)

Is this a reference to [https://youtu.be/rav29N0-h2c infinite chess by Naviary?] [[User:HaruruChanDesu|HaruruChanDesu]] ([[User talk:HaruruChanDesu|talk]]) 11:21, 5 December 2024 (UTC)

"it does not really need to consider the infinitely many pieces" => a chess Engine would need to consider the infinitely many pieces (or have a way to abstract them), even if some pieces are currently stuck because the engine recursively evaluates moves and counter-moves (i.e. evaluates the game up to some depth).

== Hit me up when this becomes real. ==

I would like to try this out. [[User:CalibansCreations|'''<span style="color:#ff0000;">Caliban</span>''']] ([[User talk:CalibansCreations|talk]]) 12:29, 5 December 2024 (UTC)
:It should be easy enough. You will rarely get the queens out in play from deep in the array. So maybe just put two chess boars together and put some placeholder in for queens in the extra fields. If ever a queen in the bottom row is moved, place extra queens that can now be moved into the 2-3 squares that would be outside the board...--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:39, 5 December 2024 (UTC)
:It might be something one could set up in Infinite Chess, although having limits on the chessboard may be difficult. [[Special:Contributions/172.68.150.67|172.68.150.67]] 14:01, 5 December 2024 (UTC)

: Here's a finite approximation in ChessCraft: https://www.chesscraft.ca/design?id=5KM4 [[User:Promethean|Promethean]] ([[User talk:Promethean|talk]]) 15:37, 5 December 2024 (UTC)

While I understand how to play chess, I don't get the bit about "having a bunch of queens doesn't go very well". At first glance, the linked chess layout looks pretty solid. Can someone please enlighten me? Also, what does the TV Tropes link about Title Drop have to do with Infinite Armada, aside from that being the title of the comic? [[Special:Contributions/172.70.230.77|172.70.230.77]] 13:10, 5 December 2024 (UTC)

:: ... Nd6. [[Special:Contributions/172.70.91.246|172.70.91.246]] 13:31, 5 December 2024 (UTC)

::: Ah, thanks. Moving the knight there puts the king in check, and moving either queen to take it exposes the king to the bishop or rook, so checkmate. [[Special:Contributions/162.158.63.38|162.158.63.38]] 15:05, 5 December 2024 (UTC)

::::You are assuming that the opponent makes no moves while you spend at least three moves advancing your knight. Looks like either side can draw by always moving the king backwards whenever a queen has moved and made a hole he can move to and otherwise trying to make a new, deeper hole. Eventually he gets so far back that any attack turns into an infinite sequence of queens taking each other, with the attacker only having file attacks while the defender can retake from a rank, file, or diagonal. Any time the attacker breaks off the infinite sequence of queens taking each other to set up something else, the defender takes advantage of the break to move the king deeper and put more queens in front of him or to create more empty spaces to sidestep into when attacked. To me, this looks like a certain draw. [[Special:Contributions/172.69.33.252|172.69.33.252]] 16:21, 5 December 2024 (UTC)

You might be able to get the developer of fairy stockfish ( https://fairy-stockfish.github.io/ ) to add this if you ask nicely. I have seen them add several reader requests. [[Special:Contributions/172.70.211.143|172.70.211.143]] 15:46, 5 December 2024 (UTC)

Could this be a reference to the meme about "eating an infinite armada of pizza"? The wording seems too similar to be a coincidence. [[Special:Contributions/172.70.114.46|172.70.114.46]] 14:46, 5 December 2024 (UTC)

Would this guarantee a draw between two competent players who'd played the variant before, or would there be more nuance to it than there appears to be?

2695: Soil

2022-11-07T17:18:25Z

172.69.33.252: Supluferous

{{comic
| number = 2695
| date = November 7, 2022
| title = Soil
| image = soil_2x.png
| imagesize = 547x217px
| noexpand = true
| titletext = You might want to bring your frost-sensitive plants in from the patio. The high-level aerosols may result in short-term cooling across the entire backyard.
}}

==Explanation==
{{incomplete|Created by an EXPLANATION SEED. Do NOT delete this tag too soon.}}

[[Beret Guy]] seems to be using {{w|volcano}} seeds to grow tiny volcanoes as an alternative to fertilizing [[Cueball]]'s garden. In reality, volcanoes are caused by the pressure of {{w|magma}} (underground lava) from below the Earth's crust pushing up through it, not seeds.

Volcanic soil is [https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-soil generally fertile], although as Cueball points out, the process of eruption is destructive to whatever plants are ''presently'' in his garden.

The title text alludes to the fact that sulfate {{w|aerosol}}s from volcanic eruptions may cause a [https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-soil short-term cooling effect], expanding on the comedy from a small scale volcano, by adding small scale volcano effects — in reality, the cooling effect occurs because the {{w|aerosol}}s in the atmosphere block out energy from the sun.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball is standing, holding a trowel. Beret Guy is kneeling, and pouring the content of a small bag in a hole in the ground.]

:Cueball: Thanks for the gardening help!

:Beret Guy: I made these seeds myself!

:[Beret Guy is standing next to a small eruption coming from the ground.]

:[Same scene, eruption is now a knee-high volcano. It produces fumes.]

:Beret Guy: The infusion of nutrient-rich volcanic soil will revitalize your garden.

:[Same scene, the volcano is now waist-high. There are flames on its sides.]

:Voice outside the picture from the direction of Cueball: All my plants are on fire.

:Beret Guy: But soon, life will return to these slopes!

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Beret Guy]]
[[Category:Strange powers of Beret Guy]]
[[Category:Volcanoes]]

2694: Königsberg

2022-11-05T22:44:17Z

172.69.33.252: /* Explanation */ typo

{{comic
| number = 2694
| date = November 4, 2022
| title = Königsberg
| image = konigsberg_2x.png
| imagesize = 448x343px
| noexpand = true
| titletext = At first I thought I would need some gold or something to pay him, but then I realized that it was the 18th century and I could just bring a roll of aluminum foil.
}}

==Explanation==
{{incomplete|Created by a WOLF, TWO GOATS, AND THREE BAGS OF GRAPH NODES. Do NOT delete this tag too soon.}}

[[File:Konigsberg bridges.png|frame|right|{{w|Königsberg}}, Prussia in Euler's time, showing the Pregel river and its seven bridges. The Baltic port city is now Kaliningrad, a Russian exclave. Two of the original seven bridges no longer exist,[https://goo.gl/maps/ChdBoeQMr3AQPi446] although there are three new bridges.]]

This comic is about the {{w|Seven Bridges of Königsberg}}, a seminal {{w|graph theory}} problem solved by the famous mathematician {{w|Leonhard Euler}}.[https://www.maa.org/press/periodicals/convergence/leonard-eulers-solution-to-the-konigsberg-bridge-problem] The problem was whether a path through the city crossing each of the seven bridges just once exists, without crossing the river forks any other way. In 1736, Euler proved that there is no such path. This result is considered to be the first theorem of graph theory and the first proof in the theory of networks[http://www-personal.umich.edu/~mejn/courses/2004/cscs535/review.pdf] — a subject now generally regarded as a branch of {{w|combinatorics}} — and presaged the development of {{w|topology}}. Combinatorial problems of other types had been considered since antiquity. {{w|Graph (discrete mathematics)|Graphs}} are a data structure common in many algorithmic problems in computer science.

[[Cueball]] attempts to cheat on the final exam in his algorithms class by traveling back in time to commission the construction of an eighth bridge before Euler could learn of the problem, allowing a trivial solution that would remove the rationale for further analysis. He hopes that this would alter his present-day timeline in such a way that the test becomes easier because graph theory might never have been developed.

With the addition of the eighth bridge, it becomes possible to cross each bridge exactly once, starting at the north bank and ending on the larger eastern island, or vice-versa. However, there is still no way to traverse each bridge exactly once and return to the starting point, because the altered graph would have a {{w|Eulerian trail|Euler trail}} but not a Euler cycle. Thus the problem might still have been sufficiently interesting to spark Euler's curiosity and develop a nearly identical general principle on the way to demonstrating that locals could indeed find no route that ended at its initial starting point. Adding a ninth bridge connecting the north bank to the east island would render the problem completely trivial and the locals may then have developed entirely different obsessions, never drawing Euler into the issue and leaving him to focus upon different problems entirely. This could backfire on Cueball, and result in an even harder topic arising in his examination, one which was never even taught to him in his original timeline experience.

An alternative modification allowing an easy solution is to remove bridges. During World War II, two bridges to the central island, connecting it to the north and south banks, were destroyed by bombing. So today there is a Eulerian trail across the five remaining bridges.

The title text alludes to the fact that ordinary {{w|aluminum foil}}, which was not commercially available until 1911, would have been a tremendously valuable curiosity in the 18th century, which didn't even have {{w|tin foil}}. Aluminum was a highly priced metal before the 1880s when inexpensive methods were developed to refine it. The {{w|Washington Monument}} was constructed with a tip made of pure aluminum due to its value and conductive capacity. Aluminum had not been extracted in its pure form at the time of Euler, and was known only in compounds such as {{w|alum}}, so the metal would have been unique and exotic.

==Transcript==

:[Cueball, standing next to two men wearing wigs, pointing with a pointer at a map showing the seven bridges problem, with an extra bridge added in dashed lines]
:Cueball: Lord Mayor of Königsberg, I will reward you handsomely if you construct this bridge before my friend Leonhard arrives.

:[Caption below the panel:]
:I tried to use a time machine to cheat on my algorithms final by preventing graph theory from being invented.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring real people]]
[[Category:Math]]
[[Category:Programming]]