Viliam Geffert
   HOME
*





Viliam Geffert
Viliam Geffert (born 1955) 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. Biography Geffert did his undergraduate studies at the P. J. Šafárik University, graduating in 1979. He earned his PhD degree in 1988 from the Comenius University Comenius University in Bratislava ( sk, Univerzita Komenského v Bratislave) is the largest university in Slovakia, with most of its faculties located in Bratislava. It was founded in 1919, shortly after the creation of Czechoslovakia. It is name ... in Bratislava. Since 2003, he is a full professor of the P. J. Šafárik University. References External links * {{DEFAULTSORT:Geffert, Viliam Slovak computer scientists Theoret ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Automata Theory
Automata theory is the study of abstract machines and automata, as well as the computational problems that can be solved using them. It is a theory in theoretical computer science. The word ''automata'' comes from the Greek word αὐτόματος, which means "self-acting, self-willed, self-moving". An automaton (automata in plural) is an abstract self-propelled computing device which follows a predetermined sequence of operations automatically. An automaton with a finite number of states is called a Finite Automaton (FA) or Finite-State Machine (FSM). The figure on the right illustrates a finite-state machine, which is a well-known type of automaton. This automaton consists of states (represented in the figure by circles) and transitions (represented by arrows). As the automaton sees a symbol of input, it makes a transition (or jump) to another state, according to its transition function, which takes the previous state and current input symbol as its arguments. Automata theo ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Computational Complexity Theory
In theoretical computer science and mathematics, computational complexity theory focuses on classifying computational problems according to their resource usage, and relating these classes to each other. A computational problem is a task solved by a computer. A computation problem is solvable by mechanical application of mathematical steps, such as an algorithm. A problem is regarded as inherently difficult if its solution requires significant resources, whatever the algorithm used. The theory formalizes this intuition, by introducing mathematical models of computation to study these problems and quantifying their computational complexity, i.e., the amount of resources needed to solve them, such as time and storage. Other measures of complexity are also used, such as the amount of communication (used in communication complexity), the number of gates in a circuit (used in circuit complexity) and the number of processors (used in parallel computing). One of the roles of computationa ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Pavol Jozef Šafárik University
Pavol Jozef Šafárik University in Košice ( Slovak ''Univerzita Pavla Jozefa Šafárika v Košiciach'') is a university located in Košice, Slovakia. It was founded in 1959 and is organized into five faculties. The university is named after Pavel Jozef Šafárik, a 19th-century Slovak philologist, poet, and historian. History The tradition of higher education in Košice goes back to the year 1657, when the bishop Benedict Kishdy founded an Academy by the Memorandum of “Studium Universale” and presented it with 40 000 tallers (by way of a dot). The Academy or the University started up managed by the Jesus’ Community Jesuits. The University of Košice Golden Bull issued on 6 August 1660 by the Roman emperor Leopold I. granted the University the same privileges as to all the other universities of the Habsburg Monarchy in Vienna, Prague, Köln, Graz, Trnava, Olomouc e.g. The Bull included a provision of high significance stating the academic degrees to be recognized as the ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Comenius University
Comenius University in Bratislava ( sk, Univerzita Komenského v Bratislave) is the largest university in Slovakia, with most of its faculties located in Bratislava. It was founded in 1919, shortly after the creation of Czechoslovakia. It is named after Jan Amos Comenius, a 17th-century Czech teacher and philosopher. In 2020, Comenius University had more about 23,000 students and 2,500 faculty members. As are most universities in Slovakia, it is funded mostly by the government. History The Comenius University was established in 1919 with assistance from the more established University of Prague. It was meant to replace the former Elisabeth University which was located in Bratislava since 1912 as the latter had been forcefully disbanded in 1919 by Samuel Zoch, plenipotentiary župan of Slovakia, after Hungarian professors refused to take an oath of allegiance at that time in the First Czechoslovak Republic. This had caused the majority of the university's professors (and some of ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


State Complexity
State complexity is an area of theoretical computer science dealing with the size of abstract automata, such as different kinds of finite automata. The classical result in the area is that simulating an n-state nondeterministic finite automaton by a deterministic finite automaton requires exactly 2^n states in the worst case. Transformation between variants of finite automata Finite automata can be deterministic and nondeterministic, one-way (DFA, NFA) and two-way (2DFA, 2NFA). Other related classes are unambiguous (UFA), self-verifying (SVFA) and alternating (AFA) finite automata. These automata can also be two-way (2UFA, 2SVFA, 2AFA). All these machines can accept exactly the regular languages. However, the size of different types of automata necessary to accept the same language (measured in the number of their states) may be different. For any two types of finite automata, the ''state complexity tradeoff'' between them is an integer function f where f(n) is the least numb ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Slovakia
Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the southwest, and the Czech Republic to the northwest. Slovakia's mostly mountainous territory spans about , with a population of over 5.4 million. The capital and largest city is Bratislava, while the second largest city is Košice. The Slavs arrived in the territory of present-day Slovakia in the fifth and sixth centuries. In the seventh century, they played a significant role in the creation of Samo's Empire. In the ninth century, they established the Principality of Nitra, which was later conquered by the Principality of Moravia to establish Great Moravia. In the 10th century, after the dissolution of Great Moravia, the territory was integrated into the Principality of Hungary, which then became the Kingdom of Hungary in 1000. In 1241 a ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Theoretical Computer Science
Theoretical computer science (TCS) is a subset of general computer science and mathematics that focuses on mathematical aspects of computer science such as the theory of computation, lambda calculus, and type theory. It is difficult to circumscribe the theoretical areas precisely. The Association for Computing Machinery, ACM's ACM SIGACT, Special Interest Group on Algorithms and Computation Theory (SIGACT) provides the following description: History While logical inference and mathematical proof had existed previously, in 1931 Kurt Gödel proved with his incompleteness theorem that there are fundamental limitations on what statements could be proved or disproved. Information theory was added to the field with a 1948 mathematical theory of communication by Claude Shannon. In the same decade, Donald Hebb introduced a mathematical model of Hebbian learning, learning in the brain. With mounting biological data supporting this hypothesis with some modification, the fields of n ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  




Two-way Finite Automaton
In computer science, in particular in automata theory, a two-way finite automaton is a finite automaton that is allowed to re-read its input. Two-way deterministic finite automaton A two-way deterministic finite automaton (2DFA) is an abstract machine, a generalized version of the deterministic finite automaton (DFA) which can revisit characters already processed. As in a DFA, there are a finite number of states with transitions between them based on the current character, but each transition is also labelled with a value indicating whether the machine will move its position in the input to the left, right, or stay at the same position. Equivalently, 2DFAs can be seen as read-only Turing machines with no work tape, only a read-only input tape. 2DFAs were introduced in a seminal 1959 paper by Rabin and Scott, who proved them to have equivalent power to one-way DFAs. That is, any formal language which can be recognized by a 2DFA can be recognized by a DFA which only examines and ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Sorting Algorithms
In computer science, a sorting algorithm is an algorithm that puts elements of a list into an order. The most frequently used orders are numerical order and lexicographical order, and either ascending or descending. Efficient sorting is important for optimizing the efficiency of other algorithms (such as search and merge algorithms) that require input data to be in sorted lists. Sorting is also often useful for canonicalizing data and for producing human-readable output. Formally, the output of any sorting algorithm must satisfy two conditions: # The output is in monotonic order (each element is no smaller/larger than the previous element, according to the required order). # The output is a permutation (a reordering, yet retaining all of the original elements) of the input. For optimum efficiency, the input data should be stored in a data structure which allows random access rather than one that allows only sequential access. History and concepts From the beginning of computi ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Košice
Košice ( , ; german: Kaschau ; hu, Kassa ; pl, Коszyce) is the largest city in eastern Slovakia. It is situated on the river Hornád at the eastern reaches of the Slovak Ore Mountains, near the border with Hungary. With a population of approximately 230,000, Košice is the second-largest city in Slovakia, after the capital Bratislava. Being the economic and cultural centre of eastern Slovakia, Košice is the seat of the Košice Region and Košice Self-governing Region, and is home to the Slovak Constitutional Court, three universities, various dioceses, and many museums, galleries, and theatres. In 2013 Košice was the European Capital of Culture, together with Marseille, France. Košice is an important industrial centre of Slovakia, and the U.S. Steel Košice steel mill is the largest employer in the city. The town has extensive railway connections and an international airport. The city has a preserved historical centre which is the largest among Slovak towns. There are ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


picture info

Bratislava
Bratislava (, also ; ; german: Preßburg/Pressburg ; hu, Pozsony) is the Capital city, capital and largest city of Slovakia. Officially, the population of the city is about 475,000; however, it is estimated to be more than 660,000 — approximately 140% of the official figures. Bratislava is in southwestern Slovakia at the foot of the Little Carpathians, occupying both banks of the River Danube and the left bank of the Morava (river), River Morava. Bordering Austria and Hungary, it is the only national capital that borders two sovereign states. The city's history has been influenced by people of many nations and religions, including Austrians, Bulgarians, Croats, Czechs, Germans, Hungarian people, Hungarians, Jews, Romani people, Romani, Serbs and Slovaks. It was the coronation site and legislative center and capital of the Kingdom of Hungary from 1536 to 1783; eleven King of Hungary, Hungarian kings and eight queens were crowned in St Martin's Cathedral, Bratislava, St Martin' ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]  


Slovak Computer Scientists
Slovak may refer to: * Something from, related to, or belonging to Slovakia (''Slovenská republika'') * Slovaks, a Western Slavic ethnic group * Slovak language, an Indo-European language that belongs to the West Slavic languages * Slovak, Arkansas, United States See also * Slovák, a surname * Slovák, the official newspaper of the Slovak People's Party Hlinka's Slovak People's Party ( sk, Hlinkova slovenská ľudová strana), also known as the Slovak People's Party (, SĽS) or the Hlinka Party, was a far-right clerico-fascist political party with a strong Catholic fundamentalist and authorit ... * {{disambiguation, geo Language and nationality disambiguation pages ...
[...More Info...]      
[...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]