2,509 research outputs found
Approximate Hypergraph Coloring under Low-discrepancy and Related Promises
A hypergraph is said to be -colorable if its vertices can be colored
with colors so that no hyperedge is monochromatic. -colorability is a
fundamental property (called Property B) of hypergraphs and is extensively
studied in combinatorics. Algorithmically, however, given a -colorable
-uniform hypergraph, it is NP-hard to find a -coloring miscoloring fewer
than a fraction of hyperedges (which is achieved by a random
-coloring), and the best algorithms to color the hypergraph properly require
colors, approaching the trivial bound of as
increases.
In this work, we study the complexity of approximate hypergraph coloring, for
both the maximization (finding a -coloring with fewest miscolored edges) and
minimization (finding a proper coloring using fewest number of colors)
versions, when the input hypergraph is promised to have the following stronger
properties than -colorability:
(A) Low-discrepancy: If the hypergraph has discrepancy ,
we give an algorithm to color the it with colors.
However, for the maximization version, we prove NP-hardness of finding a
-coloring miscoloring a smaller than (resp. )
fraction of the hyperedges when (resp. ). Assuming
the UGC, we improve the latter hardness factor to for almost
discrepancy- hypergraphs.
(B) Rainbow colorability: If the hypergraph has a -coloring such
that each hyperedge is polychromatic with all these colors, we give a
-coloring algorithm that miscolors at most of the
hyperedges when , and complement this with a matching UG
hardness result showing that when , it is hard to even beat the
bound achieved by a random coloring.Comment: Approx 201
Application of a radial basis function neural network for diagnosis of diabetes mellitus
In this article an attempt is made to study the applicability
of a general purpose, supervised feed forward
neural network with one hidden layer, namely. Radial
Basis Function (RBF) neural network. It uses relatively
smaller number of locally tuned units and is
adaptive in nature. RBFs are suitable for pattern recognition
and classification. Performance of the RBF neural
network was also compared with the most commonly used
multilayer perceptron network model and the classical
logistic regression. Diabetes database was used for
empirical comparisons and the results show that RBF
network performs better than other models
Worshipping Goddess as Mother in Tamil Literature
Human beings are afraid of natural disaster and that is how humans began to worship nature. So, man first started worshiping nature and gradually they started believing that all the things that happens in this world are caused by an invisible divine power. There the worship of man began. Based on the fact that every natural object has a power, the methods of worshiping the respective deities emerged by setting up abodes for it. Deity worship continues till today based on the feelings of devotion, gratitude and faith. Worshipping a deity will guide a man to lead a better life and it helps to mature the ignorant mind. More and more people are worshiping female deities more than worshipping male deities. Female deities are worshiped in abundance because of their respect for sex and forgiving nature like how a mother forgives her children. Through this we can understand how much importance Tamil people give to women and the worship of Mother Goddess
Diversity and distribution of microfungi in foliage leaf, bark and leaf litter of Couroupita guianensis
The diversity and distribution of micro fungal assemblages in the foliage leaf, bark and leaf litter tissues of the Couroupita guianensis sacred plant. For the host, we recorded 1005 fungal species isolates from 900 tissue segments. A total of 62 fungal species were isolated from foliar endophytes, phellophytes and leaf litter. The colonization frequency of the fungi species has been recorded as 111.66% from the endophytes, phellophytes and leaf tissues. The fungi species recovered in various groups included ascomycetes, coelomycetes, hyphomycetes, zygomycetes and sterile fungi. The number of fungal species is increased for the plant tissues, it showed that the species diversity is increasing. A correspondence analysis also showed that the fungal species assemblages were different from each type of tissue
Bioaccumulation of heavy metals in sea turtles from the west coast of India
Sea turtles are widely distributed in the tropical, sub-tropical and temperate waters. Recent
reports have indicated that their populations are threatened by the problem of marine pollution .
(Stroelli et al., 1998). Heavy metals are one of the major pollutants and have the nature to
concentrate in the tissues of animals and their concentrations vary according to biological
process such as age, sex, reproduction and migratio
Peack expiratory flow rate in South Indian Children
PEFR is a simple and reliable way of following patients with bronchial asthma and other obstructive airway diseases. Normal data is available for Caucasian and North Indian children but not for ethnic South Indian children. We, therefore, measured Peak Expiratory Flow Rate (PEFR) in 343 healthy South Indian children aged 4-15 years, using the Wright mini peak flow meter. A nomogram was constructed relating PEFR to height. Prediction equations for PEFR using height alone or height, age and weight were determined for both sexes. The prediction equation for boys based on height alone was PEFR = 4.08 height (cm) - 284.55 and for girls was PEFR = 3.92 height (cm) - 277.01
Role of nitric oxide in seed biology and seed production: A review
Nitric oxide (NO) is an important signalling molecule employed by plants to control many physiological aspects. This review summarizes that crosstalk between NO/H2O2/Ca2+ signalling pathways that drive pollen tube for sexual reproduction in flowering plants. NO is produced in seeds by both enzymatic and non-enzymatic sources that control many physiological aspects of seeds. The interplay of NO and Reactive oxygen species are likely important players in hormonal crosstalk controlling seed germination and dormancy. Mechanism of seed germination and dormancy is mainly regulated by plant hormones like Abscisic acid (ABA) and Gibberellic acid (GA). Based on mode of action of NO with reference to triggering the germination of crop seeds under abiotic stress condition it is infer that there is a linkage between NO and plant growth regulator production. NO cross-talk with reactive oxygen species (ROS) during abiotic stress condition, modulate the light and hormone depended developmental process in the early stage of plant development. NO action to enhancing abiotic stress tolerance by improving antioxidant enzymes and protection against oxidative damage in many crops are discussed in detail
Suppression of extreme events and chaos in a velocity-dependent potential system with time-delay feedback
The foremost aim of this study is to investigate the influence of
time-delayed feedback on extreme events in a non-polynomial system with
velocity dependent potential. To begin, we investigate the effect of this
feedback on extreme events for four different values of the external forcing
parameter. Among these four values, in the absence of time-delayed feedback,
for two values, the system does not exhibit extreme events and for the other
two values, the system exhibits extreme events. On the introduction of
time-delayed feedback and varying the feedback strength, we found that extreme
events get suppressed as well as get induced. When the feedback is positive,
suppression occurs for a larger parameter region whereas in the case of
negative feedback it is restricted to the limited parameter region. We confirm
our results through Lyapunov exponents, probability density function of peaks,
plot and two parameter probability plot. Finally, we analyze the
changes in the overall dynamics of this system under the influence of
time-delayed feedback. We notice that complete suppression of chaos occurs in
the considered system for higher values of the time-delayed feedback.Comment: 28 pages, 16 figures, 1 table, Accepted for Publication Chaos,
Solitons & Fractal
- …