Multislotting

Multislotting is the act of solving 2 (or more) pairs at once. This is very advanced and will cut out your movecount and time by a significant margin.

Prerequisite: Achieve a 'knowing' level of lookahead. Before solving a pair, you spot the pieces of another pair beforehand and immediately know where the pieces are going to end up.

Why do that? It will give you a general understanding of when to apply multislotting or not. A lot of the time, solving 2 pairs individually is going to be the fastest way of solving them. Knowing for example, that after solving a pair, your other pair will become an 11 mover or a free pair, you're going to know when to apply it.

Influencing

Influencing is the simplest and most elegant form of multislotting. It means altering the solution of the pair you're solving to force a better case for your other pair. This requires knowing multiple solutions for cases, although a lot of them are pretty similar (example: inserting the pair with U2 insert instead of U').

Good solution (shown above): insert FR with U2, resulting in a 3-move BR pair.

(U R U2 R') (R' U R)

Bad solution: insert FR with U', resulting in an 11-move BR pair.

(R U' R') U2 (R' U R U R' U R U' R' U R)

Good solution (shown above): insert FL with U2, resulting in a 3-move FR pair.

(U2 L' U2 L) U (R U' R')

Bad solution: insert FL with U', resulting in an 11-move FR pair.

(U' L' U L) U' (R U' R' U' R U' R' U R U' R')

The opposite may also be true: the U2 insert results in a bad case, while the U/U' doesn't.

Good solution (shown above): insert FL with U:

(U L' U L) U2 (R U R')

Bad solution: insert FL with U2:

(L' U2 L) U (R U' R' U' R U' R' U R U' R')

Influencing is mostly useful when, as stated before, you realize that after solving a pair normally, you get a very bad case. That's when you can try doing a different solution to alter the case to something better.

Pseudoslotting

Remember keyhole? Pseudoslotting is basically that, but you solve both an edge of one pair and the corner of another pair to solve 2 pairs at once. You can treat the edge and corner that you're solving much like a F2L pair, but because they don't match, the recognition relies entirely on the position of the two pieces and the orientation of the corner.

Here's an example: DFR and FL are solved. If open slots are available, you could use keyhole to solve the DFL and FR pieces one-by-one, like this:

Keyhole the FR edge, then the DFL corner: (D R U2 R' D') (D2 R' U' R D2)

With pseudoslotting, you can do that all at once. Here, we can do a D move to align the unsolved corner and edge spots, forming a "pseudo-slot". Then we treat the DFL corner and FR edge much like a regular F2L pair:

Moves: D (R U R' U2 R U' R') D'

The advantages of pseudoslotting compared to doing keyhole twice:

• Works even with no other open-slots.
• Fewer D moves for better ergonomics, and often fewer moves in total.
• Recognition in one step.

That's cool when it appears, but you can also force a pseudoslotting case! If we have an edge or a corner solved, we can insert the other corner/edge and then pseudoslot. This is very overpowered, but make sure you're forcing a case that makes sense. In this example, the regular F2L pairs are both 7-movers, not great. But an edge is solved, so we can solve a corner of another slot. Then, pseudoslot!

Moves: (R U' R') (D R U' R' D')

When to force? You will see from practice and experimenting, but generally when you can solve both pairs in 8-9 moves this way (like the above example) it's good to use it.

Pseudo F2L

Where you offset your EOCross by a D move (or any D move to that extent) and solve the pieces from here like you would do in pseudoslotting. The main aspect is that sometimes you shouldn't do this for the entirety of F2L: you could do this for 2 pairs but then have normal free pairs appear, this is when you should switch.

This technique is difficult to learn also mainly for pair recognition: you would have to get accustomed to the colours of your pseudo pairs, which will require a lot of practice.

Once mastered however, it's a very powerful tool. You'll be able to cut down your movecount significantly and be able to get sub 50 move solutions with ease when the opportunity arrises.

Algorithms

Now, some multislotting cases (mainly Last 2 pairs) are pretty complicated in terms on what influencing or pseudoslotting technique you should use, and some cases are just so bad even with these techniques that you could use algorithms for them, although these cases will be rare if you have good pair choice. Biggest example is when you have 2 pairs solved, and the rest of the F2L pieces end up in the F2L slots but not inserted in their spots or the corners may end up misoriented, which are worthwhile learning sets with not that many algorithms in them.

You can use the currently available multislotting alg sheets to learn algs for these cases, although think about this when you have already mastered the other aspects of F2L.

ZZ Last 2 Pairs Sheet (opens in a new tab)