We prove that the identity checking problem in a finite semigroup S is co-NP-complete whenever S has a nonsolvable subgroup or S is the semigroup of all transformations on a 3-element set. 1 Motivation and Main Results Many basic algorithmic questions in algebra whose decidability is well known and/or obvious give rise to fascinating and sometimes very hard problems if one looks for the computa...

[1] In this study, the performance of inverse threedimensional variational assimilation (I3D-Var) is investigated in terms of dissipation process for an advection-diffusion problem. The performance of I3D-Var becomes poorer with larger diffusion coefficients. However, even for strong dissipation, the cost function during early iterations in the I3D-Var decreases still much faster than it does i...

introduction: the purpose of this study was formulation and preparation of a proper culture medium for saccharomyces cerevisiae var. boulardii with molasses and animal serum. methods: a fully-crossed factorial design contain 5%, 10% and 20% of molasses (m) with 0, 1% and 5% animal serum (s) was used in this study. the ph of all culture medias were adjusted to 5.6 with acetic acid. the seed was ...

This paper develops a new test to evaluate Value at Risk (VaR) forecasts. VaR is a standard risk measure widely utilized by financial institutions and regulators, yet estimating VaR is a challenging problem, and popular VaR forecast relies on unrealistic assumptions. Hence, assessing the performance of VaR is of great importance. We propose the geometric-VaR test which utilizes the duration bet...

BACKGROUND Human cryptococcal infections have been associated with bird droppings as a likely source of infection. Studies toward the local and global epidemiology of Cryptococcus spp. have been hampered by the lack of rapid, discriminatory, and exchangeable molecular typing methods. METHODOLOGY/PRINCIPAL FINDINGS We selected nine microsatellite markers for high-resolution fingerprinting from...

In this paper, we examine the risk characteristics and capital adequacy of hedge funds using Value-at-Risk (VaR) as the criterion for measuring risk and estimating capital requirements. We find that a vast majority of hedge funds are adequately capitalized, with the level of under-capitalization being only 3.1% for live funds and 7.5% for dead funds. Using extreme value theory, we confirm that ...

• Distribution 2: Pr(0) = Pr(50) = Pr(100) = 1/3. Both have the same expectation: 50. But the first is much less “dispersed” than the second. We want a measure of dispersion. • One measure of dispersion is how far things are from the mean, on average. Given a random variable X , (X(s) − E(X)) measures how far the value of s is from the mean value (the expectation) of X . Define the variance of ...

Recent DNA sequencing data have shown that J. flaccida var. flaccida, J. f. var. martinezii and J. f. var. poblana are polyphyletic taxa. Additional analysis using Random Amplified Polymorphic DNAs (RAPDs) analyses for J. durangensis, J. flaccida var. flaccida, var. martinezii, and var. poblana, J. jaliscana, J. monticola and J. standleyi revealed exactly the same pattern of relationships as se...