Viliam Geffert | Academic Influence

Viliam Geffert's AcademicInfluence.com Rankings

Viliam Geffert

Computer Science

#10472

World Rank

#11000

Historical Rank

Theoretical Computer Science

#150

World Rank

#150

Historical Rank

Database

#9727

World Rank

#10291

Historical Rank

computer-science Degrees

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Computer Science

Viliam Geffert's Degrees

PhD Computer Science Comenius University

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Best Online PhD of Computer Science (Doctorates) 2025

Why Is Viliam Geffert Influential?

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According to Wikipedia, Viliam Geffert is a Slovak theoretical computer scientist known for his contributions to the computational complexity theory in sublogarithmic space and to the state complexity of two-way finite automata. He has also developed new in-place sorting algorithms. He is a professor and the head of the computer science department at the P. J. Šafárik University in Košice.

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Viliam Geffert's Published Works

Number of citations in a given year to any of this author's works

Total number of citations to an author for the works they published in a given year. This highlights publication of the most important work(s) by the author

Published Works

SOFSEM 2008: Theory and Practice of Computer Science, 34th Conference on Current Trends in Theory and Practice of Computer Science, Nový Smokovec, Slovakia, January 19-25, 2008, Proceedings (2008) (86)
Normal forms for phrase-structure grammars (1991) (80)
Converting Two-Way Nondeterministic Unary Automata into Simpler Automata (2003) (57)
Complementing Two-Way Finite Automata (2007) (55)
Magic numbers in the state hierarchy of finite automata (2006) (45)
Nondeterministic Computations in Sublogarithmic Space and Space Constructibility (1990) (42)
Context-Free-Like Forms for the Phrase-Structure Grammars (1988) (41)
An in-place sorting with O(n log n) comparisons and O(n) moves (2003) (41)
Hyper-minimizing minimized deterministic finite state automata (2009) (38)
More concise representation of regular languages by automata and regular expressions (2008) (31)
A Hierarchy That Does Not Collapse: Alternations in Low Level Space (1994) (26)
Tally Versions of the Savitch and Immerman-Szelepcsenyi Theorems for Sublogarithmic Space (1993) (25)
Classical Automata on Promise Problems (2014) (24)
SOFSEM 2014: Theory and Practice of Computer Science (2014) (21)
Bridging Across the log(n) Space Frontier (1995) (21)
A Lower Bound for the Nondeterministic Space Complexity of Context-Free Recognition (1992) (20)
Two-way unary automata versus logarithmic space (2010) (20)
The size-cost of Boolean operations on constant height deterministic pushdown automata (2011) (19)
Removing nondeterminism in constant height pushdown automata (2012) (18)
Translation of binary regular expressions into nondeterministic ε-free automata with transitions (2003) (18)
An alternating hierarchy for finite automata (2012) (17)
Boolean language operations on nondeterministic automata with a pushdown of constant height (2013) (17)
Space hierarchy theorem revised (2003) (15)
Sublogarithmic Bounds on Space and Reversals (1999) (13)
Transforming Two-Way Alternating Finite Automata to One-Way Nondeterministic Automata (2014) (13)
A Representation of Recursively Enumerable Languages by Two Homomorphisms and a Quotient (1988) (13)
How to Generate Languages Using Only Two Pairs of Parentheses (1991) (13)
(Non)determinism and the Size of One-Way Finite Automata (2005) (12)
Two-way automata making choices only at the endmarkers (2011) (12)
Grammars with Context Dependency Restricted to Synchronization (1986) (10)
Normal forms for phrase-structure grammars. Theoretical Informatics and Applications (1991) (9)
New Results on the Minimum Amount of Useful Space (2014) (9)
Sublogarithmic Sigma2-Space is not Closed under Complement and Other Separation Results (1993) (9)
A Speed-Up Theorem Without Tape Compression (1990) (8)
Unary Coded NP-Complete Languages in ASPACE (log log n) (2012) (8)
A Communication Hierarchy of Parallel Computations (1998) (7)
Translation from classical two-way automata to pebble two-way automata (2009) (6)
Multiway in-place merging (2009) (6)
One-way simulation of two-way finite automata over small alphabets (2013) (5)
Two double-exponential gaps for automata with a limited pushdown (2014) (5)
State Hierarchy for One-Way Finite Automata (2007) (4)
Speed-Up Theorem Without Tape Compression (1990) (4)
Complement for two-way alternating automata (2020) (4)
Pairs of Complementary Unary Languages with “Balanced” Nondeterministic Automata (2012) (4)
Factoring and testing primes in small space (2009) (3)
Proceedings of the 34th conference on Current trends in theory and practice of computer science (2008) (3)
Alternating space is closed under complement and other simulations for sublogarithmic space (2017) (3)
Pairs of Complementary Unary Languages with “Balanced” Nondeterministic Automata (2010) (3)
In-Place Sorting (2011) (3)
Unary Coded PSPACE-Complete Languages in ASPACE(loglog n) (2017) (2)
A Direct Construction of Finite State Automata for Pushdown Store Languages (2013) (2)
Input-Driven Pushdown Automata for Edit Distance Neighborhood (2019) (2)
Unary Coded NP-Complete Languages in Aspace(log log n) (2013) (2)
A variant of inductive counting (2000) (1)
Conversion of regular expressions into realtime automata (2006) (1)
Linear-Time In-Place Selection with epsilon.n Element Moves (2012) (1)
Alternating Demon Space Is Closed Under Complement and Other Simulations for Sublogarithmic Space (2016) (1)
Improved complement for two-way alternating automata (2022) (1)
Multiway blockwise in-place merging (2008) (1)
One Pebble Versus log(n) Bits. (2009) (1)
Hyper-Minimizing Minimized Deterministic Automata (2008) (0)
Complement for two-way alternating automata (2020) (0)
Deterministic One-Way Simulation of Two-Way Deterministic Finite Automata over Small Alphabets (2021) (0)
State Complexity of Binary Coded Regular Languages (2022) (0)
One Pebble Versus epsilon * log n Bits (2009) (0)
Refinement of the Alternating Space Hierarchy (2002) (0)
Minimal Size of Counters for (Real-Time) Multicounter Automata (2021) (0)
Unary Coded PSPACE-Complete Languages in ASPACE(loglog n) (2018) (0)
SOFSEM 2008: Theory and Practice of Computer Science, 34th Conference on Current Trends in Theory and Practice of Computer Science, Nový Smokovec, Slovakia, January 19-25, 2008, Volume II - Student Research Forum (2008) (0)
A space lower bound for acceptance by one-way II2-alternating machines (2000) (0)
Acknowledgement to Referees (2000) (0)
Minimal Useful Size of Counters for (Real-Time) Multicounter Automata (2018) (0)

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