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20G validity of the {J,L} reduction

Prove that the NP-hardness reduction for Tetris clearing under the Super Rotation System (SRS) using the two-piece set {J, L} (Proposition JL) also works when pieces experience 20G gravity, i.e., instant maximal downward movement before lock.

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Background

The paper provides NP-hardness proofs for Tetris clearing with various two-piece sets under standard SRS, with some results also holding in the "20G" model, where pieces immediately drop to their maximal height. For the {J, L} case, the authors conjecture the construction still functions under 20G but did not complete the verification of required rotations under that mode.

Establishing this would extend the catalog of two-piece NP-hardness results that apply in high-gravity variants of modern Tetris.

References

Conjecture. The reduction in the proof of Proposition \ref{prop:JL} works even if pieces experience 20G gravity.

— Tetris with Few Piece Types (2404.10712 - Group et al., 16 Apr 2024) in Section 4.6 (Remaining Subsets with More Complex Structures), following Proposition \ref{prop:JL}