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On the gap between separating words and separating their reversals
, Article Theoretical Computer Science ; 2017 ; 03043975 (ISSN) ; Sharif University of Technology
Elsevier B.V
2017
Abstract
A deterministic finite automaton (DFA) separates two strings w and x if it accepts w and rejects x. The minimum number of states required for a DFA to separate w and x is denoted by sep(w,x). The present paper shows that the difference |sep(w,x)-sep(wR,xR)| is unbounded for a binary alphabet; here wR stands for the mirror image of w. This solves an open problem stated in Demaine et al. (2011) © 2017 Elsevier B.V
On the gap between separating words and separating their reversals
, Article Theoretical Computer Science ; Volume 711 , February , 2018 , Pages 79-91 ; 03043975 (ISSN) ; Sharif University of Technology
Elsevier B.V
2018
Abstract
A deterministic finite automaton (DFA) separates two strings w and x if it accepts w and rejects x. The minimum number of states required for a DFA to separate w and x is denoted by sep(w,x). The present paper shows that the difference |sep(w,x)−sep(wR,xR)| is unbounded for a binary alphabet; here wR stands for the mirror image of w. This solves an open problem stated in Demaine et al. (2011) [2]. © 2017 Elsevier B.V
Short-sale constraints and stock price informativeness
, Article Global Finance Journal ; Volume 40 , May , 2018 , Pages 28-34 ; 10440283 (ISSN) ; Hoseinzade, S ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Morck, Yeung, and Yu (2000), in their pioneering study of international differences in stock price synchronicity, emphasize the effect of market development on investors' ability to incorporate firm-specific information into prices. We use a unique institutional feature in the Hong Kong market to investigate one of the important tools investors use to do this and hence reduce stock price synchronicity: short selling. Examining the cross-sectional and time-series variation in short-sale constraints in the Hong Kong market, we find that after the removal of short-sale constraints, stock prices become more informative and move less in tandem with the market. © 2018 Elsevier Inc
Short-sale constraints and stock price informativeness
, Article Global Finance Journal ; Volume 40 , 2019 , Pages 28-34 ; 10440283 (ISSN) ; Hoseinzade, S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Morck, Yeung, and Yu (2000), in their pioneering study of international differences in stock price synchronicity, emphasize the effect of market development on investors' ability to incorporate firm-specific information into prices. We use a unique institutional feature in the Hong Kong market to investigate one of the important tools investors use to do this and hence reduce stock price synchronicity: short selling. Examining the cross-sectional and time-series variation in short-sale constraints in the Hong Kong market, we find that after the removal of short-sale constraints, stock prices become more informative and move less in tandem with the market
Investigating Market Reaction to Asset Revaluation
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
In recent years, some listed companies have re-evaluated their assets, an event that has generally received market attention; In fact, the market seems to be reacting very positively to an accounting phenomenon. In this study, we seek to investigate the market reaction to the revaluation of listed companies in Iran. To do this, we first estimate the market reaction to the news of the revaluation of assets. We then examine the possible reasons for the market reaction to the revaluation. Asset revaluation can improve the firm's access to finance by improving some financial ratios; On the other hand, the increase in capital from the revaluation of firms is accompanied by the issuance of bonus...
Market Manipulation before Block Trades: Evidence from the Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
Price manipulation can lead to lack of transparency and impair proper functioning of financial markets. On the Tehran Stock Exchange, there is ample anecdotal evidence that some blockholders try to manipulate the price before the block transactions to change the share price significantly. In this paper, we provide empirical evidence that in intergroup block trades, blockholders tend to buy shares before the trade date or engage in round-trip transactions to increase the block shares price. No such evidence is found in intragroup transactions and other explanations such as market reaction to a change in corporate ownership seem more plausible than price manipulation. In addition to the...
The Relationship Between Common Ownership and Competitive Conditions of Corporations: Evidence from the Iranian Stock Market
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
The impact of ownership concentration on competitive conditions and profitability of industries has been studied and analyzed for decades. By using the Herfindahl-Hirschman concentration index, a range for the level of concentration in the industry has been determined, and some countries implement anti-trust laws based on this range. The new literature that has been discussed recently is the concentration of the market directly and through the common ownership of corporations by large shareholders. In the sense that two or more apparently independent companies may have a common owner who practically regulates their behavior as a company. The structure of ownership in Iran is complex and...
The Relationship Between Ownership Structure and Performance: Evidence from the Iranian Stock Market
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
Pyramidal and network ownership structures that provide ultimate owners with more control over companies are common in the Iranian stock market. Given the multi-layered shareholding networks and the significant changes that have occurred in the ownership structure of large Iranian companies in the last two decades, the purpose of this study is to investigate the relationship between ownership structure and performance of companies. To achieve this purpose, ownership structure is examined using four measures; cash flow right of the largest shareholder, the wedge between control right and cash flow right of the largest shareholder, difference in cash flow rights of the largest two...
Privatization and Firm Performance: Evidence from Iran`s Privatization Experience
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
Privatization in Iran was primarily driven by the 2004 amendment to the Article 44 of the Iranian Constitution. Improving firms' efficiency is cited as the key goal of the privatization program. The two prominent characteristics of the privatization program in Iran are complex ownership structure and transferring ownership from the government to government-affiliated institutions and organizations. For these reasons, the consequences of privatization in Iran may differ from those of other countries. Therefore, this study explores the relation between privatization and firm performance, as measured by firm efficiency, labor efficiency, investment, and the number of employees. As a significant...
Investigating the Rank Effect in the Trading Behavior of Iranian Mutual Funds
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
The rank effect means that investors are more likely to sell the best or worst positions in their portfolio in terms of returns. According to this effect, the probability of selling a stock in a prominent position (first or last) is higher than other stocks in the portfolio. Apart from being a behavioral bias, the rank effect is that the decision to sell a stock depends on how it is compared and ranked with the rest of the portfolio. In this study, we examine the rank effect on the trading behavior of Iranian mutual funds for the period 1390-1399 and find that it is significant. First in a statistical and univariate form, and then by including other variables such as firm-specific...
Tunneling: Evidence from Business Groups of Iran
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
Objective: Business groups that create pyramidal ownership structures are a common form of corporate ownership in developing countries such as India, Chile, and Iran. These groups, along with the benefits they create, separate voting rights from cash flow rights; As a result, the ultimate owner will control them while having a small share of the cash flows of the companies in the lower layers of the group. This phenomenon provides tunneling motivation for controlling owners; incentivizing them to transfer resources and assets of their subsidiary companies (transferring resources from companies with less cash flow rights to companies with more cash flow rights) to gain private benefits at the...
Determinants of the Quality of Corporate Social Responsibility Disclosures in Iran’s Stock Market
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
This study examines the quality of Corporate Social Responsibility (CSR) disclosure among publicly listed companies in Iran and identifies the factors that influene it. The research sample consists of 546 companies listed on the Tehran Stock Exchange and Iran Fara Bourse, covering the period from February 2023 to January 2024. Data were extracted from audited financial statements and the annual reports of the companies' boards of directors. In the first part of the study, a CSR disclosure quality index comprising 39 factors was developed. The annual reports of the companies were then analyzed to calculate a disclosure score for each company. The average CSR disclosure quality score was...
Information Content of Price Discovery Process in Preopening of the Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
As an initial step in understanding the issue of disputed spoofing orders in the Tehran Stock Exchange (TSE), this paper empirically analyzes the limit order book data of the market from 2010 to 2024. The findings demonstrate—consistent with the existing literature—that the pre-opening phase of the TSE contains valuable informational content. Notably, the study identifies evidence of learning over time during the pre-opening phase, accompanied by a significant increase in informational content as the market approaches its opening. These results align with both theoretical and empirical studies in this domai. The analysis further reveals that factors such as company size play a crucial role...
A comparative study of different approaches for finding the upper boundary points in stochastic-flow networks
, Article International Journal of Enterprise Information Systems ; Volume 10, Issue 3 , 1 July , 2014 , Pages 13-20 ; ISSN: 15481115 ; Nasseri, S. H ; Forghani Elahabad, M ; Ebrahimnejad, A ; Sharif University of Technology
2014
Abstract
An information system network (ISN) can be modeled as a stochastic-flow network (SFN). There are several algorithms to evaluate reliability of an SFN in terms of Minimal Cuts (MCs). The existing algorithms commonly first find all the upper boundary points (called d-MCs) in an SFN, and then determine the reliability of the network using some approaches such as inclusion-exclusion method, sum of disjoint products, etc. However, most of the algorithms have been compared via complexity results or through one or two benchmark networks. Thus, comparing those algorithms through random test problems can be desired. Here, the authors first state a simple improved algorithm. Then, by generating a...
A new extended analytical hierarchy process technique with incomplete intervalvalued information for risk assessment in IT outsourcing
, Article International Journal of Engineering, Transactions B: Applications ; Volume 30, Issue 5 , 2017 , Pages 739-748 ; 1728144X (ISSN) ; Gitinavard, H ; Sohrabvandi, S ; Sharif University of Technology
2017
Abstract
Information technology (IT) outsourcing has been recognized as a new methodology in many organizations. Yet making an appropriate decision with regard to selection and use of these methodologies may impose uncertainties and risks. Estimating the occurrence probability of risks and their impacts organizations goals may reduce their threats. In this study, an extended analytical hierarchical process method is tailored based on interval-valued hesitant fuzzy information to assess the risks in IT outsourcing. In the proposed approach, the weight of each decision maker is implemented in process of the proposed method by considering the concept of simple additive weighting method to decrease the...
Studying the Effect of Connection with Private Banks on Companies in Iran
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
This research examines the effect of the relationship between firms and private banks on the behavior and performance of firms. For this purpose, the data of the relationship of non-financial listed firms with private banks, as well as the available data from the characteristics of these firms, have been used. The dataset of this research is an unbalanced panel of firms between 2004 and 2014, in which the characteristics of the firm and the connection or non-connection of the firm with private banks are specified in each year. In the following, with the help of these data and the method of propensity score matching and difference in difference, the main question of the research has been...
New approximation functions in the meshless finite volume method for 2D elasticity problems
, Article Engineering Analysis with Boundary Elements ; Vol. 46, issue , Sep , 2014 , p. 10-22 ; Fallah, N ; Khoei, A. R ; Sharif University of Technology
2014
Abstract
In this paper, two new approximation functions are introduced. These new techniques, which are referred herein as the multi-triangles method (MTM) and weighted multi-triangles method (WMTM) are applied for the approximation of unknowns and their derivatives at the points of interest. The approximations are performed in terms of the unknowns corresponding to the field nodes which are the vertices of the region surrounding the desired point and determined by Delaunay triangulations. The capability and accuracy of the proposed approximation functions are compared with the other approximating techniques in the meshless finite volume (MFV) frame work for some benchmark problems. Numerical...
Adaptive refinement in the meshless finite volume method for elasticity problems
, Article Computers and Mathematics with Applications ; Volume 69, Issue 12 , June , 2015 , Pages 1420-1443 ; 08981221 (ISSN) ; Fallah, N ; Khoei, A. R ; Sharif University of Technology
2015
Abstract
In this paper, two adaptive refinement techniques are presented for enhancing the capability of the new kind of finite volume method called meshless finite volume (MFV) method in which the moving least squares (MLS) approximation technique is employed. The proposed algorithms perform by inserting new nodes in large error regions identified using the Zienkiewicz-Zhu (Z-Z) error estimator and the T-Belytschko (TB) stress recovery scheme. In the first method referred as CV-based adaptive refinement, the new nodes are inserted at the vertices of control volumes with higher errors. The second method, referred as GA-based adaptive refinement, contains two schemes where an adaptive refinement...
Three types of meshless finite volume method for the analysis of two-dimensional elasticity problems
, Article Computational and Applied Mathematics ; Volume 36, Issue 2 , 2017 , Pages 971-990 ; 01018205 (ISSN) ; Fallah, N ; Khoei, A. R ; Sharif University of Technology
Springer Science and Business Media, LLC
2017
Abstract
This paper presents three schemes of 2D meshless finite volume (MFV) method, referred to as MFV with overlapping control volumes (MFV1), MFV with irregular non-overlapping control volumes (MFV2) and MFV with regular non-overlapping control volumes (MFV3). The methods utilize the local symmetric weak form of system equation and the interpolation functions constructed using the weighted multi-triangles method (WMTM) which is recently developed by the present authors. The proposed formulation involves only integrals over the boundaries of control volumes. The performance of the proposed schemes is studied in three benchmark problems. A comparative study between the predictions of the above MFV...
Investigating the Trading Behavior of Institutional Investors in Response to Market Fluctuations
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor)
Abstract
In the present study, we examine the behavior of institutional investors in response to fluctuations in the Iranian stock market. Specifically, we examine the question of whether, in significant market fluctuations, institutional investors engage in grievous trading behavior and follow market trends or move in the opposite direction of the market and provide liquidity. For this purpose, we examine the relationship between the percentage of ownership of institutional shareholders and the stock price return and the trading volume of companies in severe market fluctuations. Also, we obtain the relationship between the percentage of ownership of institutional shareholders and stock price returns...