CFOP method: Difference between revisions

Revision as of 13:15, 17 June 2024

Revision as of 13:29, 17 June 2024

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Speedcubers are generally given 15 seconds to inspect the cube. They are allowed to rotate the cube, but not to make any moves.

When using the CFOP method, cubers generally use this time to look at how to solve the cross. More advanced cubers can also look ahead into F2Ltheir first pair ("Cross + 1") and can even set up their first pair to be solved faster by altering their cross solution.

===Cross===

This first stage of solving involves solving the four edge pieces around one center, matching the colors of that center and each of the adjacent centers, forming the eponymous cross shape on the first layer. Most beginner methods start with the daisy, which is putting the white edge pieces required to solve the cross around the yellow center, then matching them with the same colored center, and moving them down to match them with the white center. However, while the beginner method typically recommends doing the daisy, most CFOP tutorials recommend solving the cross on the bottom side to avoid cube rotations and to get an overall better view of the important pieces needed for the next step (F2L). If the solver is particularly advanced, they could skip the first pair and solve an "X-cross" (the cross and a first pair solved at the same time).<ref>{{Cite web |title=XCross - Speedsolving.com Wiki |url=https://www.speedsolving.com/wiki/index.php?title=Extended_cross |access-date=2024-06-17 |website=www.speedsolving.com}}</ref> This is usually done using a technique called Keyhole, which solves one piece of the first pair while ignoring the other one.<ref>{{Cite web |title=Keyhole F2L - Speedsolving.com Wiki |url=https://www.speedsolving.com/wiki/index.php?title=Keyhole |access-date=2024-06-17 |website=www.speedsolving.com}}</ref>

This step is usually performed intuitively, although some techniques, such as replacement, and edge orientation. The white cross is most commonly used for demonstration and by beginner and intermediate speedsolvers, though more advanced speedcubers can use any of the six colors to form the cross (choosing the one that requires the fewest/easiest moves), a practice known as "color neutrality".<ref>{{cite web | url=https://www.cubeskills.com/blog/colour-neutrality | title=Colour Neutrality }}</ref> Cross can always be solved in 8 moves or less.<ref>{{Cite web |title=CubeZone - Cross study |url=http://www.cubezone.be/crossstudy.html |access-date=2023-08-05 |website=www.cubezone.be}}</ref>

[[File:CfopF2L.svg|alt=|thumb|First Two Layers (F2L) solved|210x210px]]

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===Orient Last Layer (OLL)===

This stage involves manipulating the top layer (yellow, if the cross is solved on white) so that all the pieces have the correct color on top, while largely ignoring the sides of these pieces. This stage involves a total of 57 algorithms, each solving a unique permutation of the top layer in a single sequence. A simpler version, called "two-look OLL", orients the edges first to produce a cross, then uses a second algorithm to orient the corners. This reduces the 57 algorithms down to 10.: 3 for edge orientation and 7 for orientating the corners. The three algorithms - Dot, L and Line - are used for edge orientation, and seven - Sune, Antisune, Pi, H, Bowtie, Headlights and T - for corner orientation. Edge orientation in two-look is commonly taught as two algorithms, one of which is a simple variation of the other; the Dot case is solved by performing both algorithms consecutively. Additionally, the required algorithms for corner orientation can be reduced to just two, the Sune and Antisune, as all other permutations can be solved either by performing two Sunes or a Sune followed by an Antisune. Additional algorithms, more efficient than the Sune-Antisune sequences, can be learned at the solver's own pace.

===Permute Last Layer (PLL)===

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Depending on the initial state of the cube and the exact moves made in previous stages, it is possible to complete one stage in such a way that the next stage is also already complete. This is known as a "skip", commonly referred to specifically by the stage that isn't required in the solve. A "PLL skip" is the most common, occurring (when "unforced") approximately once in 72 solves, followed by an OLL skip with a 1 in 216 chance to occur. A combination of the two, a full "Last Layer Skip", occurs approximately once in 15,552 solves. The Cross and F2L stages of a competition-legal scramble are almost certainly not skippable, though a scramble may present the solver with "free" cross pieces or F2L pairs that are already solved or matched. As speedsolving time is closely related to the number of moves required, any opportunity to make fewer moves presents a significant advantage to the solver. Many speedsolvers have the ability, falling under the general skillset of "lookahead", to identify the likely permutation they will see for the next stage based on the progress of the current stage, and they can vary their solution to avoid permutations that require more moves or an algorithm they are slower to perform. This same ability can allow the solver, in specific known scenarios, to "force" a stage skip with a particular sequence of moves to solve the remainder of the current stage; for instance, by recognizing a particular OLL permutation and performing a specific OLL algorithm, the solver can simultaneously solve PLL, effectively obtaining a PLL skip.<ref>{{Cite web|title=PLL Skip Cases - Sarah's Cubing Site|url=https://sarah.cubing.net/3x3x3/pll-skip-cases|access-date=2022-12-16}}</ref>

There also exist many advanced extension algorithm sets to be used alongside CFOP, such as COLL,<ref>{{Cite web |title=COLL |url=https://jperm.net/algs/coll |access-date=2022-09-18 |website=jperm.net}}</ref> Winter Variation,<ref>{{Cite web |title=Winter Variation |url=https://jperm.net/algs/wv |access-date=2022-09-18 |website=jperm.net}}</ref> VLS, ZBLL, and more. However, it is not necessary to learn them in order to solve the cube or to use the CFOP method. These sets usually have extreme numbers of algorithms; ZBLL has a total of 472 of them. Therefore, most solvers do not learn these sets and instead focus on improving their skills within regular CFOP.

==Competition use==