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| | ==Explanation== | | ==Explanation== |
| | + | {{incomplete|Created by a LIVE MINEFIELD. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}} |
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| − | This comic, like [[1897: Self Driving]], references the approach of using human-entered {{w|CAPTCHA}} inputs to solve {{w|machine learning}} problems, particularly those involving image classification. | + | This comic, like [[1897: Self Driving]], references the approach of using {{W|CAPTCHA}} inputs to solve problems, particularly those involving image classification, which are not solvable by computers, specifically {{W|reCAPTCHA}} v2's fallback puzzle which is based on identifying road features and vehicles. A reCAPTCHA version of this puzzle might ask a user to "check all squares containing a STOP SIGN." |
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| − | In order to prevent automated programs from using web services, Google offers a protection called {{w|reCAPTCHA}}, which performs various tests to see if a user is human or machine. One of these tests is a "I'm not a robot" checkbox which must be checked in order to proceed, although ticking the box is merely a formality, and later versions of reCAPTCHA can simply perform the tests quietly in the background without needing user consent.
| + | The CAPTCHA in this comic, however, asks the user to "Click all the pictures of MINES" by, ironically, clicking on squares that do not show anything more than a gray square, with the understanding that some of those gray squares are hiding 'mines' in a {{w|Minesweeper (video game)|Minesweeper puzzle game}}, hence the title Mine Captcha. |
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| − | If the reCAPTCHA system suspects that the user may be an automated bot, it presents an image recognition challenge that only humans should be able to pass. This has the desired effect of denying access to robots, but it also has a side benefit that the human input can be used to train Google's image recognition software. The challenge usually features a square grid of images, typically things one might see while driving - e.g. "Check all squares containing a stop sign". If the user clicks enough correct squares, they are permitted to continue.
| + | Furthermore, the CAPTCHA in this comic asks the user to click on the squares containing mines themselves, which is the opposite of the traditional goal in Minesweeper, which is to click on all boxes where there are *no* mines, and solving the puzzle is usually (although not in this case) impossible without revealing the information in those squares without mines. So the CAPTCHA in this comic would be especially difficult for a user who is familiar with how to play Minesweeper, in addition to being difficult for a user who is familiar with the normal CAPTCHA image-selection puzzle. But would be impossible for anyone that have never heard of the game/know the rules. |
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| − | {{w|Minesweeper (video game)|Minesweeper}}, on the other hand, is a logic puzzle game in which the player is presented with a grid of unrevealed squares and must deduce the location of mines that have been secretly hidden on random squares. The game provides clues by marking some squares with the number of mines (up to a maximum of 8) that are adjacent to that square; by carefully considering the possibilities, a player can deduce which squares must contain mines, and mark them with flags to avoid clicking on them. Revealing a mine loses the game.
| + | A captcha (also spelled CAPTCHA) is a challenge designed to be solvable by humans, but not by computer programs. It is used to protect websites from automated software. For example, editing the explain xkcd wiki without being logged in requires the user to solve a Captcha. |
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| − | In this comic, Randall combines the two concepts to create a "Mine Captcha", which is presented in the form of a reCAPTCHA challenge but actually appears to be a mini game of Minesweeper. To be more precise, it is actually the ''opposite'' of regular Minesweeper. This challenge invites the user to click on the mines, as opposed to Minesweeper's aim of clicking only upon unrevealed squares that are ''not'' mines. Furthermore, within the terms of a reCAPTCHA, there are no ''pictures'' of mines displayed, to click upon. This is also the case for Minesweeper, as they only appear once the game ends, all remaining hidden during play and thus needing to be deduced where they all are.
| + | The captcha depicted in this comic is similar in layout to one of the challenges of ''reCAPTCHA'', a captcha system developed by Google. It requires the user to click on several of 16 tiles laid out in a 4x4 grid. 6 of the 16 tiles has a colored number, in blue font for the three number ones, green for the single instance of two and red for the two number three. Each number used a different font style disregarding the color. |
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| − | A real-world Mine Captcha would be somewhat ineffective for a variety of reasons. Firstly, not every human would recognize a game of Minesweeper and therefore wouldn't understand what they are being asked to do. Even if they do recognize the game, they may not know the logical method for deducing the locations of mines. Additionally, even for skilled players, there is a trap in that the Captcha's objective is the reverse of regular Minesweeper; they might therefore get tripped up by muscle memory and click on something that is not a mine, which would fail the challenge.
| + | The comic combines this with the game of Minesweeper, a logic puzzle game where the player must uncover tiles in a grid by clicking on them. Some of the tiles contain "mines", clicking on those means immediate defeat. When uncovering a tile without a mine, it shows how many of the 8 adjacent tiles contain a mine. |
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| − | Another issue is that games of Minesweeper can sometimes involve a degree of luck, as it is possible to generate a puzzle which does not give sufficient information to unambiguously deduce the location of every mine. This may not be a problem since Randall's Minesweeper is only a four-by-four grid. In these situations, the most a player can do is click the uncertain square and hope for the best. If the Mine Captcha is poorly implemented in this way, this would increase false negatives in human detection due to some humans failing the captcha purely due to bad luck. Some variants attempt to eliminate this problem: ''[https://pragmada.x10hosting.com/mindet.html Mine Detector]'', for example, is a variant game which provides better information, such that it's almost always solvable without guessing except at the highest difficulty level.
| + | This comic expects users click on the mines in a minesweeper puzzle to proceed with their task. As the goal in minesweeper is to click on boxes where there are NOT mines, the puzzle would be especially difficult for anyone used to playing minesweeper. In addition, as long as a computer could be made to read and understand the task (presuming there is no obfuscation of the instruction or grid), a logic puzzle such as this is a case where an automated spambot could actually be prepared to more easily solve the puzzle than most people. |
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| − | Finally, a Mine Captcha would actually be fairly easy for an artificial intelligence to solve, since it is a logic puzzle: as long as the AI can read the numbers, it can simply use an algorithm to eliminate all impossibilities until it has the correct answer. With a 4x4 grid it's even easier than that: a computer could quickly brute force the problem by trying every possible arrangement of mines until it has the correct one.
| + | The comic shows a 4x4 grid with mostly grey squares, and a few tiles showing colored numbers. The setup and colors suggest a gaming board of the popular minesweeper game, with a few tiles uncovered. Numbers would then show the number of mines in adjacent squares. Given the current board configuration, one can deduce that there are four mines (in squares A2, B2, B3 and D3, where letters (numbers) mark columns (rows)), see [[#Trivia|trivia section]]. For example, there are two mines within the squares A2,B1,B2, as signified by the 2 in A1, but only one of those can be in B1 or B2 (because of the 1 in C1). Therefore, A2 has to be a mine. The title suggests this as a CAPTCHA, where proving to be human involves first recognizing this as a minesweeper simile, and then solving for those squares with mines. |
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| − | It seems that Randall predicted that an AI might try to solve the captcha itself, as he rendered each numeral in a different style; this is similar to obfuscation methods used in text-based captchas to prevent automatic text recognition software from reading the captcha. However, it would not be very effective in this case as the same numbers have the same color; an AI could simply recognize the color instead, which is even easier for an AI than trying to read a number.
| + | <pre> |
| | + | A B C D |
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| | + | 1 2 . 1 . |
| | + | 2 * * 3 . |
| | + | 3 3 * . * |
| | + | 4 . 1 . 1 |
| | + | </pre> |
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| − | The title text is similar to [[1897: Self Driving]] where the CAPTCHA solver is asked to answer quickly, implying that the training data is actually a real-world situation being experienced by a self-driving vehicle at that very moment. The joke here is that real-life minefields do not have large numbers indicating which of the surrounding land contains mines{{citation needed}}.
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| − | ==Solving the Mine Captcha==
| + | Traditionally, the goal in minesweeper is to click on boxes where there are NOT mines, and solving the puzzle is usually (although not in this case) impossible without revealing the information in those squares, so the puzzle could easily trip up anyone used to playing minesweeper. |
| − | Assuming that columns are denoted by letters A, B, C, D, left to right, and rows are denoted by 1, 2, 3, 4, top to bottom, one way to solve the captcha is as follows:
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| − | The leftmost red 3 at A3 is surrounded by four squares (A2, B2, B3, A4), of which we know three are mines. Therefore, one of these squares is not a mine. However, because of the blue 1 at B4, we know that only one of B3 and A4 can be a mine, otherwise, there would be more than one mine adjacent to B4; therefore, '''A2''' and '''B2''' ''must'' be mines. Otherwise, there could only be two total mines adjacent to A3. | + | The title text is similar to [[1897: Self Driving]] where the CAPTCHA solver is asked to "answer quickly – [the] self-driving car is almost at the intersection", as a parody of the current tendency for CAPTCHAs to apparently be used to provide training information in order to improve automatic identification of traffic signals, pedestrian crosswalks, bicycles, buses and other potential road hazards. In this case the car is apparently driving into this minefield and can only avoid the mines if the user solves this CAPTCHA fast enough for immediate application of the input. Where the first would be realistic, although very dangerous, this time it is of course just a continuation of that old joke. Even if the car drove into a mine field, there would be no way to have the limited 'clue' information (with typically just the one complete and unambiguous solution) and yet somehow not already be able to have more knowledge of the 'answer' than the CAPTCHA user. |
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| − | <font color="green">2</font> . <font color="blue">1</font> .
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| − | <font color="violet">X X</font> <font color="red">3</font> .
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| − | <font color="red">3</font> . . .
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| − | . <font color="blue">1</font> . <font color="blue">1</font>
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| − | Since A1 is a green 2 and is adjacent to two squares that we now know are mines (A2 and B2), this means that B1 is ''not'' a mine. If it was, there would be 3 adjacent mines to A1. Furthermore, since there is a blue 1 at C1, and we know that the adjacent B2 is a mine, this means that D1 and D2 are also ''not'' mines, since if any of them were, there would be more than one mine adjacent to C1.
| + | ==Transcript== |
| − | | + | {{incomplete transcript|Do NOT delete this tag too soon.}} |
| − | <font color="green">2</font> <font color="gold">O</font> <font color="blue">1</font> <font color="gold">O</font>
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| − | <font color="violet">X X</font> <font color="red">3</font> <font color="gold">O</font>
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| − | <font color="red">3</font> . . .
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| − | . <font color="blue">1</font> . <font color="blue">1</font>
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| − | We also know that C3 and C4 are ''not'' mines, since we already know that the blue 1 at B4 is next to exactly one mine (on either B3 or A4). Since this eliminates two of the three possible neighbors of the blue 1 at D4, this means that '''D3''' ''must'' be a mine.
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| − | <font color="green">2</font> <font color="gold">O</font> <font color="blue">1</font> <font color="gold">O</font>
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| − | <font color="violet">X X</font> <font color="red">3</font> <font color="gold">O</font>
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| − | <font color="red">3</font> . <font color="gold">O</font> <font color="violet">X</font>
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| − | . <font color="blue">1</font> <font color="gold">O</font> <font color="blue">1</font>
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| − | Finally, since we now know the locations of two of the mines around the red 3 at C2, and we have eliminated all other possibilities, '''B3''' ''must'' be a mine. Therefore, the mines are at '''A2''', '''B2''', '''B3''', and '''D3'''. This solves the puzzle.
| + | [A "CAPTCHA" box.] |
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| − | <font color="green">2</font> <font color="gold">O</font> <font color="blue">1</font> <font color="gold">O</font>
| + | To proceed, click<br>all the pictures of<br>MINES |
| − | <font color="violet">X X</font> <font color="red">3</font> <font color="gold">O</font>
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| − | <font color="red">3</font> <font color="violet">X</font> <font color="gold">O</font> <font color="violet">X</font>
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| − | <font color="gold">O</font> <font color="blue">1</font> <font color="gold">O</font> <font color="blue">1</font>
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| − | ==Transcript==
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| − | :[A Minesweeper game in a 4x4 grid is shown beneath a blue rectangle. There is an explanation in white text in the blue field:]
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| − | :To proceed, click all the pictures of '''<big>Mines</big>'''
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| − | :[The ''Minesweeper'' field has six cells with revealed numbers on a light gray background. The other 10 fields are empty and dark gray. The three ones are blue, the single two are green and the two threes are red. On top of this each number is drawn in a different font/style. The ones changes how bold they are. The two is drawn in a 3D format, the one three is very thin and the other is drawn with two lines and no filling in between (hollow). The grid looks like this:]
| + | [A 4 by 4 ''Minesweeper'' field, with some cells revealed with numbers. Each number is drawn in a different font/style.] |
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| − | <font color="green">2</font> . <font color="blue">1</font> .
| + | <pre> |
| − | . . <font color="red">3</font> .
| + | 2 . 1 . |
| − | <font color="red">3</font> . . .
| + | . . 3 . |
| − | . <font color="blue">1</font> . <font color="blue">1</font>
| + | 3 . . . |
| | + | . 1 . 1 |
| | + | </pre> |
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| | ==Trivia== | | ==Trivia== |
| − | *The solved version of the puzzle showing where the mines are in this comic: | + | *Here is where the mines are in this comic, and thus the fields that needs to be pushed in this Captcha to prove you are human: |
| | :[[File:2946_Mine_Captcha_With_Bombs.png]] | | :[[File:2946_Mine_Captcha_With_Bombs.png]] |
| − | *The solved puzzle as it would look if played as a real minesweeper game, except the mines would be represented by flags. The empty square top right corner has 0 bombs next to it. This is not written in the game but indicated as this field has been pushed down: | + | *Here are the solved puzzle as it would look if played as a real minesweeper game, except the mines would be represented by flags. (The empty square top right corner has 0 bombs next to it. This is not written in the game but indicated as this field has been pushed down): |
| | :[[File:2946_Mine_Captcha_Solved.png]] | | :[[File:2946_Mine_Captcha_Solved.png]] |
| | *The original game can be played here: [https://minesweeper.online/ World of Minesweeper] | | *The original game can be played here: [https://minesweeper.online/ World of Minesweeper] |
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| | [[Category:CAPTCHA]] | | [[Category:CAPTCHA]] |
| | [[Category:Self-driving cars]] | | [[Category:Self-driving cars]] |
| − | [[Category:Comics with color]]
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