9 papers found.

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We study selective monitors for labelled Markov chains. Monitors observe the outputs that are generated by a Markov chain during its run, with the goal of identifying runs as correct or faulty. A monitor is selective if it skips observations in order to reduce monitoring overhead. We are interested in monitors that minimize the expected number of observations. We establish an...

We prove results on the decidability and complexity of computing the total variation distance (equivalently, the L_1-distance) of hidden Markov models (equivalently, labelled Markov chains). This distance measures the difference between the distributions on words that two hidden Markov models induce. The main results are: (1) it is undecidable whether the distance is greater than...

Given finite-state automata (or context-free grammars) A,B over the same alphabet and a Parikh vector p, we study the complexity of deciding whether the number of words in the language of A with Parikh image p is greater than the number of such words in the language of B. Recently, this problem turned out to be tightly related to the cost problem for weighted Markov chains. We...

Nonnegative matrix factorization (NMF) is the problem of decomposing a given nonnegative n*m matrix M into a product of a nonnegative n*d matrix W and a nonnegative d*m matrix H. Restricted NMF requires in addition that the column spaces of M and W coincide. Finding the minimal inner dimension d is known to be NP-hard, both for NMF and restricted NMF. We show that restricted NMF...

optimal. 1998 ACM Subject Classification F.1.2 Modes of Computation ? Full version at http://arxiv.org/abs/1504.01130. ? **Stefan** **Kiefer** is supported by a University Research Fellowship of the Royal Society

/0340);
his short visit at Oxford was also supported by ESF-GAMES grant no. 4513. **Stefan** **Kiefer**
is supported by the EPSRC.
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In CAV , pages 50 - 61 , 1996 .
S. B?hm , S

the Czech Science Foundation, grant No. P202/10/1469. **Stefan** **Kiefer** is supported by a DAAD postdoctoral fellowship.
and phrases continuous-time Markov decision processes; infinite-state systems

LIPIcs.STACS.
COMPUTING LEAST FIXED POINTS OF PROBABILISTIC SYSTEMS OF POLYNOMIALS
JAVIER ESPARZA
ANDREAS GAISER
**STEFAN** **KIEFER**
We study systems of equations of the form X1 = f1(X1, . . . , Xn

LIPIcs.STACS.
COMPUTING LEAST FIXED POINTS OF PROBABILISTIC SYSTEMS OF POLYNOMIALS
JAVIER ESPARZA
ANDREAS GAISER
**STEFAN** **KIEFER**
We study systems of equations of the form X1 = f1(X1, . . . , Xn