5x5 last two edges

[Jezzular]

According to https://www.speedcubedb.com/a/5x5/L2E there are 13 cases.
On Feliks Site are only 12 https://www.cubeskills.com/tutorials/last-2-edges-algorithms-5x5
What am I missing?

 

[OreKehStrah]

According to https://www.speedcubedb.com/a/5x5/L2E there are 13 cases.
On Feliks Site are only 12 https://www.cubeskills.com/tutorials/last-2-edges-algorithms-5x5
What am I missing?

The first 2 cases on scdb are just mirrors. That’s where extra case is coming from

 

[xyzzy]

The 13th case on SCDB was added because I asked Gil to add it. That one case is conspicuously missing from the majority of "modern" L2E resources (including CubeSkills, Meep, etc. etc. etc.). The late addition also explains why, despite being an even-parity L2E case, it's grouped together with the odd-parity L2E cases instead of the other even-parity L2E cases.

(Ironically, I don't even use the alg there. This variation is probably a bit faster: r' U' R U r2 U R U' r2 U' R U r.)

 

[Jezzular]

Thx for that fast reply. But why are all other resources missing that case? They must be aware of it?
I can argue, that I can do the Flipping Alg to Setup into case 4. But that is also true for case 7&8 for Exemple.
So either I count all cases then there are 15 (1&2 can also be flipped) or I dont count cases, where I can do Setups, then I have 7 cases. Am I missing sth in my constistency claim? I am very confused.

 

[xyzzy]

Sometimes things happen for no good reason (or they happen for bad reasons). This is one of those things. The inconsistency was not the result of a conscious decision; it just happened.

Top solvers like Feliks definitely are aware that this case exists; they can solve it without a second thought. But because everyone copies everyone else's resources, omissions like this can go unfixed for long periods of time.

One popular but incomplete resource goes out of fashion, but the replacement resource copied from it so it has the same omissions. There are complete resources (e.g. Robert Yau's L2E list), but they're unpopular and new resources don't copy from unpopular resources.

 

[Jezzular]

Thx a lot. That helped a lot. With your help I found this site https://www.cuberoot.me/5x5-yau-l2e/ with all 15 cases. Now I am reliefed.
But still wondering... Imagine every site would only list 20 PLL for 3x3, instead of 21. Where are all the beginners getting confused. There should be a ton of threads asking for help.

 

[artless1der]

curious, are some of the cases over 12 inherent in the Yau 5 method? (I use Redux + Roux)
edit: I remember in one of his TUESDAY TIPS videos Kevin Hays referring to 12 L2E algs...
and
on Sarah Strong's website (she credits Meep) she shows 13 cases, but one case is the L2E solved state

 

[Jezzular]

curious, are some of the cases over 12 inherent in the Yau 5 method? (I use Redux + Roux)
edit: I remember in one of his TUESDAY TIPS videos Kevin Hays referring to 12 L2E algs...
and
on Sarah Strong's website (she credits Meep) she shows 13 cases, but one case is the L2E solved state

No they are not inherent. Here are all 15 cases for Redux:
https://www.cuberoot.me/5x5-l2e/

I suppose some cases are skipped in most Lists, because with some Setup moves you can transform them into other cases. But that is also true for some cases that are listed. So I think xyzzy answer fits best here.

 

[artless1der]

No they are not inherent. Here are all 15 cases for Redux:
https://www.cuberoot.me/5x5-l2e/

I suppose some cases are skipped in most Lists, because with some Setup moves you can transform them into other cases. But that is also true for some cases that are listed. So I think xyzzy answer fits best here.

some of those cases shown there do not appear to be discrete L2E cases, as a slice-flip-slice solves them

In Redux that wouldn't make any difference, one would just perform that operation and go on with the solve...,
but the color scheme they show on that page seems to indicate their significances to YAU as there is no blue-red color-pair but instead red-white coupled with the green-orange color-pair...
I can see however that they do seem to be proposing algs one could employ in Yau5 to avoid messing up the cross-edges built in an earlier step in that method

So I guess if you use CFOP and Yau5 that could come in handy

 

[xyzzy]

There should be a ton of threads asking for help.

Beginners aren't looking for L2E algs.

(Full L2E is comparable to full PLL in terms of usefulness and difficulty so I find it a bit bizarre that people put off learning it so frequently.)

edit: I remember in one of his TUESDAY TIPS videos Kevin Hays referring to 12 L2E algs...

He says in episode 11: "I think there's only like 12 or so".

According to a comment left by Meep in that video's comments, there used to be an alg for the missing case on his website, but he removed it because the alg sucks. By the time Kevin made this Tuesday Tips video (March 2017), the alg was already no longer on Meep's website. The oldest snapshot on the Wayback Machine is dated July 2013, and at that point it was already missing this case.

Yau versus plain redux does not affect the number of L2E cases. (The specific edge pairing strategy used might affect the likelihoods of the different L2E cases, but this applies equally to all reasonable reduction-like methods, and in any case, it won't make certain L2E cases outright impossible.)

 

[Jezzular]

some of those cases shown there do not appear to be discrete L2E cases, as a slice-flip-slice solves them

Slice-flip-slice is still an algorithm and mathematically a case. It is like saying, some 3x3 OLLs don't count, because a simple Sune solves them.
And https://www.cubeskills.com/tutorials/last-2-edges-algorithms-5x5 here the first two cases are also only slice-flip-slice.