Generic commutative separable algebras and cospans of graphs.
Halteprobleme von Fang-Systemen (Tag Systems).
Hierarchy of reversal bounded one-way multicounter machines
Highly Undecidable Problems For Infinite Computations
We show that many classical decision problems about 1-counter ω-languages, context free ω-languages, or infinitary rational relations, are Π½ -complete, hence located at the second level of the analytical hierarchy, and “highly undecidable”. In particular, the universality problem, the inclusion problem, the equivalence problem, the determinizability problem, the complementability problem, and the unambiguity problem are all Π½ -complete for context-free ω-languages or for infinitary rational...
Immunity and simplicity in relativizations of probabilistic complexity classes
K metodice řešení hybridních obvodů grafy signálových toků
Limit probabilities for random sparse bit strings.
Local transition functions of quantum Turing machines
Local Transition Functions of Quantum Turing Machines
Foundations of the notion of quantum Turing machines are investigated. According to Deutsch's formulation, the time evolution of a quantum Turing machine is to be determined by the local transition function. In this paper, the local transition functions are characterized for fully general quantum Turing machines, including multi-tape quantum Turing machines, extending the results due to Bernstein and Vazirani.
Lower bounds on the complexity of real-time branching programs
Multigenerative grammar systems and matrix grammars
Multigenerative grammar systems are based on cooperating context-free grammatical components that simultaneously generate their strings in a rule-controlled or nonterminal-controlled rewriting way, and after this simultaneous generation is completed, all the generated terminal strings are combined together by some common string operations, such as concatenation, and placed into the generated languages of these systems. The present paper proves that these systems are equivalent with the matrix grammars....
Natural quantum operational semantics with predicates
A general definition of a quantum predicate and quantum labelled transition systems for finite quantum computation systems is presented. The notion of a quantum predicate as a positive operator-valued measure is developed. The main results of this paper are a theorem about the existence of generalised predicates for quantum programs defined as completely positive maps and a theorem about the existence of a GSOS format for quantum labelled transition systems. The first theorem is a slight generalisation...
Nondeterminism is essential for reversal-bounded two-way multihead finite automata
Nonuniform complexity classes specified by lower and upper bounds
Number-conserving reversible cellular automata and their computation-universality
We introduce a new model of cellular automaton called a one-dimensional number-conserving partitioned cellular automaton (NC-PCA). An NC-PCA is a system such that a state of a cell is represented by a triple of non-negative integers, and the total (i.e., sum) of integers over the configuration is conserved throughout its evolving (computing) process. It can be thought as a kind of modelization of the physical conservation law of mass (particles) or energy. We also define a reversible version of...
Number-Conserving Reversible Cellular Automata and Their Computation-Universality
We introduce a new model of cellular automaton called a one-dimensional number-conserving partitioned cellular automaton (NC-PCA). An NC-PCA is a system such that a state of a cell is represented by a triple of non-negative integers, and the total (i.e., sum) of integers over the configuration is conserved throughout its evolving (computing) process. It can be thought as a kind of modelization of the physical conservation law of mass (particles) or energy. We also define a reversible version...
On free Turing algebras
On hierarchy of the positioned eco-grammar systems
Positioned eco-grammar systems (PEG systems, for short) were introduced in our previous papers. In this paper we engage in a new field of research, the hierarchy of PEG systems, namely in the hierarchy of the PEG systems according to the number of agents presented in the environment and according to the number of types of agents in the system.
On the complexity of the hidden weighted bit function for various BDD models
On the Complexity of the Hidden Weighted Bit Function for Various BDD Models
Ordered binary decision diagrams (OBDDs) and several more general BDD models have turned out to be representations of Boolean functions which are useful in applications like verification, timing analysis, test pattern generation or combinatorial optimization. The hidden weighted bit function (HWB) is of particular interest, since it seems to be the simplest function with exponential OBDD size. The complexity of this function with respect to different circuit models, formulas, and various...