Compressed Subsequence Checking is PSPACE-complete

Markus Lohrey

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arXiv · 2609.14490

Compressed Subsequence Checking is PSPACE-complete

Markus Lohrey

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Abstract

It is shown that the (scattered) subsequence problem for two words represented by straight-line programs is PSPACE-complete, even over a binary alphabet. The lower bound is obtained by a polynomial-time reduction from quantified subset sum.

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Markus Lohrey. 2026-09-13. Compressed Subsequence Checking is PSPACE-complete. https://arxiv.org/abs/2609.14490

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