Stefan Hoffmann 0001

dblp:73/962-1 · DBLP profile ↗
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26ranked-venue papers
24as first author
22since 2021 · last 2026
0000-0002-7866-075XORCID · verified

Domains — the database's venue-derived domains; a paper can count in several

Theory of computation · 25 · 23 first-author · 21 since 2021Applied, interdisciplinary, general and emerging computing · 1 · 1 first-author · 1 since 2021
YearPublicationVenuePosition
2026 Completely Distinguishable Automata and the Set of Synchronizing Words
Stefan Hoffmann 0001
Theory Comput. Syst.1
2026 Synchronization of Parikh Automata
Stefan Hoffmann 0001
Theory Comput. Syst.1
2025 The n-ary initial literal and literal shuffle
Stefan Hoffmann 0001
Discret. Appl. Math.1
2024 Automata Classes Accepting Languages Whose Commutative Closure is Regular
Stefan Hoffmann 0001
SOFSEM1
2024 State complexity bounds for projection, shuffle, up- and downward closure and interior on commutative regular languages
Stefan Hoffmann 0001
Inf. Comput.1
2023 Synchronization of Parikh Automata
Stefan Hoffmann 0001
DLT1
2023 Completely Distinguishable Automata and the Set of Synchronizing Words
Stefan Hoffmann 0001
DLT1
2023 Binary and circular automata having maximal state complexity for the set of synchronizing words
Stefan Hoffmann 0001
Inf. Comput.1
2023 New characterizations of primitive permutation groups with applications to synchronizing automata
Stefan Hoffmann 0001
Inf. Comput.1
2022 Automata-Theoretical Regularity Characterizations for the Iterated Shuffle on Commutative Regular Languages
Stefan Hoffmann 0001
DLT1
2022 Constrained Synchronization for Monotonic and Solvable Automata and Automata with Simple Idempotents
Stefan Hoffmann 0001
CIAA1
2021 Ideal Separation and General Theorems for Constrained Synchronization and Their Application to Small Constraint Automata
Stefan Hoffmann 0001
COCOON1
2021 State Complexity of Projection on Languages Recognized by Permutation Automata and Commuting Letters
Stefan Hoffmann 0001
DLT1
2021 Constrained Synchronization and Subset Synchronization Problems for Weakly Acyclic Automata
Stefan Hoffmann 0001
DLT1
2021 Computational Complexity of Synchronization Under Sparse Regular Constraints
Stefan Hoffmann 0001
FCT1
2021 On the Complexity of Intersection Non-emptiness for Star-Free Language Classes
abstract
In the Intersection Non-Emptiness problem, we are given a list of finite automata $A_1,A_2,\dots,A_m$ over a common alphabet $Σ$ as input, and the goal is to determine whether some string $w\in Σ^*$ lies in the intersection of the languages accepted by the automata in the list. We analyze the complexity of the Intersection Non-Emptiness problem under the promise that all input automata accept a language in some level of the dot-depth hierarchy, or some level of the Straubing-Thérien hierarchy. Automata accepting languages from the lowest levels of these hierarchies arise naturally in the context of model checking. We identify a dichotomy in the dot-depth hierarchy by showing that the problem is already NP-complete when all input automata accept languages of the levels zero or one half and already PSPACE-hard when all automata accept a language from the level one. Conversely, we identify a tetrachotomy in the Straubing-Thérien hierarchy. More precisely, we show that the problem is in AC$^0$ when restricted to level zero; complete for LOGSPACE or NLOGSPACE, depending on the input representation, when restricted to languages in the level one half; NP-complete when the input is given as DFAs accepting a language in from level one or three half; and finally, PSPACE-complete when the input automata accept languages in level two or higher. Moreover, we show that the proof technique used to show containment in NP for DFAs accepting languages in the Straubing-Thérien hierarchy levels one ore three half does not generalize to the context of NFAs. To prove this, we identify a family of languages that provide an exponential separation between the state complexity of general NFAs and that of partially ordered NFAs. To the best of our knowledge, this is the first superpolynomial separation between these two models of computation.
Emmanuel Arrighi, Henning Fernau, Stefan Hoffmann 0001, Markus Holzer 0001, Ismaël Jecker, Mateus de Oliveira Oliveira, Petra Wolf 0002
FSTTCS3
2021 Completely Reachable Automata, Primitive Groups and the State Complexity of the Set of Synchronizing Words
Stefan Hoffmann 0001
LATA1
2021 State Complexity of the Set of Synchronizing Words for Circular Automata and Automata over Binary Alphabets
Stefan Hoffmann 0001
LATA1
2021 Regularity Conditions for Iterated Shuffle on Commutative Regular Languages
Stefan Hoffmann 0001
CIAA1
2021 The Commutative Closure of Shuffle Languages over Group Languages is Regular
Stefan Hoffmann 0001
CIAA1
2021 State Complexity of Permutation and Related Decision Problems on Alphabetical Pattern Constraints
Stefan Hoffmann 0001
CIAA1
2021 Constrained synchronization and commutativity
Stefan Hoffmann 0001
Theor. Comput. Sci.1
2020 Computational Complexity of Synchronization Under Regular Commutative Constraints
Stefan Hoffmann 0001
COCOON1
2019 Computational Complexity of Synchronization under Regular Constraints
Henning Fernau, Vladimir V. Gusev, Stefan Hoffmann 0001, Markus Holzer 0001, Mikhail V. Volkov 0001, Petra Wolf 0002
MFCS3
2017 Shift-invariant topologies for the Cantor space Xω
Stefan Hoffmann 0001, Sibylle Schwarz, Ludwig Staiger
Theor. Comput. Sci.1
2015 Subword Metrics for Infinite Words
Stefan Hoffmann 0001, Ludwig Staiger
CIAA1