# HSC

 Hollow Stairs & Columns method Information about the method Proposer(s): Imam Tanvin Alam Proposed: 2019 Alt Names: Hollow Squares & Columns, Hollow String & Columns Variants: Direct Solve, Corners First, Orient First, Permute First, Reduce First No. Steps: 3 major No. Algs: 0 (8, 16, 32 or 90 with algorithmic approach) Avg Moves: ~40-50 STM Purpose(s): Experimental (Speedsolving, FMC, One-Handed Solving possible)

HSC, short for Hollow Stairs & Columns, has similarities with several other methods: Morozov and Columns first, SSC and ECE, Belt and Domino Reduction, Human Thistlethwaite Algorithm and Kociemba Algorithm.

But unlike all other Columns first and Corners first methods (except SSC), HSC solves Corner orientation and Belt edges orientation simultaneously.

Another unique feature is HSC can be implemented in such a way that EO, CO and CP steps can be done in any sequence, as long as EP is done at the end.

## Method Overview

Similar to Roux, HSC is quite intuitive (in the sense that the cuber is fully aware of every move that are being made and understands what each turn is doing, and relies less on rote memorization).

With relatively few algorithms (mostly common triggers) and tolerably low move count, beginner HSC is easy to understand and easy to implement.

It is also one of the most flexible methods (several steps can be swapped or mixed and matched to suit the objective/situation/scramble), making it particularly appealing to those who enjoy fun, novel and elegant ways to solve. This feature also makes HSC a good option for FMC style solving (serving as a Skeleton in particular).

HSC may also be suitable for one handed solving, since it allows CP and EO to be done early in the solve, thus reducing the cube to <R, U, M, D> moves. All of its variants can be virtually rotationless, additionally the Direct Solve variants can be virtually regripless.

## General Structure

1. Hollow Stairs
2. Hollow Columns
3. End Game

1. Hollow Stairs = build two (oriented, but not necessarily permuted) "L" shaped blocks in DLF and DLB (meaning Petrus style 2x2x3 block, minus the centers and the S slice edge)

Additionally R/L centers may be placed on R/L faces (making a Hollow String of pieces on the left side), or F/B centers may be placed on F/B faces (making two Hollow Squares on F and B layers)

2. Hollow Columns = place four (oriented, but not necessarily permuted) "I" shaped blocks in LF, LB, RB and RF (meaning CFOP style F2L pairs, plus the LL corners)

3. Permute the corners (before or after the Hollow Stairs and Hollow Columns steps) with <R, U> and <L, U> moves

4. Orient the edges (before, after, or in-between the Hollow Stairs and Hollow Columns steps) with F/B moves or <M, U> moves

5. End Game = finish the solve as a 3x3x2 domino puzzle (meaning <F2, B2, R2, L2, U, D> moves are enough)

## Pros

• Ergonomic, mostly <R, U, M, D>
• Low algorithm count compared to more popular speedsolving methods
• High level of flexibility

## Cons

• Can be difficult to transition from other popular methods
• Pseudoblocks can be difficult to get used to
• M slice moves may also be difficult for some people