theoretical-computer-science / Automata and formal languages; regular expressions

A uniform bound of three on generalized star height (the generalized star-height problem)

Claims Theorem 1.1: for every finite alphabet Σ\Sigma and every regular L⊆Σ∗L\subseteq\Sigma^*, h(L)≤3h(L)\le3, using expressions over Σ\Sigma itself with complement in Σ∗\Sigma^*. Companions prove the weaker bounds 13 and 4 by different constructions. It does NOT exhibit any language of generalized star height greater than one, does not decide whether height one always suffices, gives no algorithm for computing h(L)h(L), and bounds neither expression size nor running time.

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theoretical-computer-scienceSep 25, 2026Significance 30/100Registry: lean checked

A uniform bound of three on generalized star height (the generalized star-height problem)

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Claims Theorem 1.1: for every finite alphabet Σ\Sigma and every regular L⊆Σ∗L\subseteq\Sigma^*, h(L)≤3h(L)\le3, using expressions over Σ\Sigma itself with complement in Σ∗\Sigma^*. Companions prove the weaker bounds 13 and 4 by different constructions. It does NOT exhibit any language of generalized star height greater than one, does not decide whether height one always suffices, gives no algorithm for computing h(L)h(L),…

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Claims Theorem 1.1: for every finite alphabet Σ\Sigma and every regular L⊆Σ∗L\subseteq\Sigma^*, h(L)≤3h(L)\le3, using expressions over Σ\Sigma itself with complement in Σ∗\Sigma^*. Companions prove the weaker bounds 13 and 4 by different constructions. It does NOT exhibit any language of generalized star height greater than one, does not decide whether height one always suffices, gives no algorithm for computing h(L)h(L), and bounds neither expression size nor running time.

Claims Theorem 1.1: for every finite alphabet Σ\Sigma and every regular L⊆Σ∗L\subseteq\Sigma^*, h(L)≤3h(L)\le3, using expressions over Σ\Sigma itself with complement in Σ∗\Sigma^*. Companions prove the weaker bounds 13 and 4 by different constructions. It does NOT exhibit any language of generalized star height greater than one, does not decide whether height one always suffices, gives no algorithm for computing h(L)h(L), and bounds neither expression size nor running time.

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A uniform bound of three on generalized star height (the generalized star-height problem) — Mathematical Frontier Network