Using TPA to count linear extensions
نویسندگان
چکیده
A linear extension of a poset P is a permutation of the elements of the set that respects the partial order. Let L(P ) denote the number of linear extensions. It is a #P complete problem to determine L(P ) exactly for an arbitrary poset, and so randomized approximation algorithms that draw randomly from the set of linear extensions are used. In this work, the set of linear extensions is embedded in a larger state space with a continuous parameter β. The introduction of a continuous parameter allows for the use of a more efficient method for approximating L(P ) called TPA. Our primary result is that it is possible to sample from this continuous embedding in time that as fast or faster than the best known methods for sampling uniformly from linear extensions. For a poset containing n elements, this means we can approximate L(P ) to within a factor of 1+ ǫ with probability at least 1 − δ using an expected number of random bits and comparisons in the poset which is at most O(n3(lnn)(lnL(P ))2ǫ−2 ln δ−1).
منابع مشابه
Drift Change Point Estimation in the rate and dependence Parameters of Autocorrelated Poisson Count Processes Using MLE Approach: An Application to IP Counts Data
Change point estimation in the area of statistical process control has received considerable attentions in the recent decades because it helps process engineer to identify and remove assignable causes as quickly as possible. On the other hand, improving in measurement systems and data storage, lead to taking observations very close to each other in time and as a result increasing autocorrelatio...
متن کاملMonte Carlo Modeling of Dual and Triple Photon Energy Absorptiometry Technique
Introduction: Osteoporosis is a bone disease in which there is a reduction in the amount of bone mineral content leading to an increase in the risk of bone fractures. The affected individuals not only have to go through lots of pain and suffering but this disease also results in high economic costs to the society due to a large number of fractures. A timely and accurate diagnosis of this disea...
متن کاملPosition Isomerism on One and Two Photon Absorption in Multibranched Chromophores: A TDDFT Investigation.
Recently, branching and click chemistry strategies have been combined to design a series of optically active chromophores built from triazole moieties. These triazole-based multipolar chromophores have been shown to be promising candidates for two-photon absorption (TPA) transparency optimization in perspective of optical limiting in the visible region. In this work, the nature of one- and two-...
متن کاملIntravenous Tissue Plasminogen Activator Can Be Safely Given without Complete Blood Count Results Back
INTRODUCTION It is well known that the efficacy of intravenous (i.v.) tissue plasminogen activator (tPA) is time-dependent when used to treat patients with acute ischemic strokes. AIM Our study examines the safety issue of giving IV tPA without complete blood count (CBC) resulted. MATERIALS AND METHODS This is a retrospective observational study by examining the database from Huashan Hospit...
متن کاملCount Time Series Models
We review regression models for count time series. We discuss the approach which is based on generalized linear models and the class of integer autoregressive processes. The generalized linear models framework provides convenient tools for implementing model fitting and prediction using standard software. Furthermore, this approach provides a natural extension to the traditional ARMA methodolog...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- CoRR
دوره abs/1010.4981 شماره
صفحات -
تاریخ انتشار 2010