Non-oblivious Strategy Improvement

We study strategy improvement algorithms for mean-payoff and parity games. We describe a structural property of these games, and we show that these structures can affect the behaviour of strategy improvement. We show how awareness of these structures can be used to accelerate strategy improvement algorithms. We call our algorithms non-oblivious because they remember properties of the game that they have discovered in previous iterations. We show that non-oblivious strategy improvement algorithms perform well on examples that are known to be hard for oblivious strategy improvement. Hence, we argue that previous strategy improvement algorithms fail because they ignore the structural properties of the game that they are solving

The Complexity of All-switches Strategy Improvement

Strategy improvement is a widely-used and well-studied class of algorithms for solving graph-based infinite games. These algorithms are parameterized by a switching rule, and one of the most natural rules is "all switches" which switches as many edges as possible in each iteration. Continuing a recent line of work, we study all-switches strategy improvement from the perspective of computational complexity. We consider two natural decision problems, both of which have as input a game $G$, a starting strategy $s$, and an edge $e$. The problems are: 1.) The edge switch problem, namely, is the edge $e$ ever switched by all-switches strategy improvement when it is started from $s$ on game $G$? 2.) The optimal strategy problem, namely, is the edge $e$ used in the final strategy that is found by strategy improvement when it is started from $s$ on game $G$? We show $\mathtt{PSPACE}$-completeness of the edge switch problem and optimal strategy problem for the following settings: Parity games with the discrete strategy improvement algorithm of V\"oge and Jurdzi\'nski; mean-payoff games with the gain-bias algorithm [14,37]; and discounted-payoff games and simple stochastic games with their standard strategy improvement algorithms. We also show $\mathtt{PSPACE}$-completeness of an analogous problem to edge switch for the bottom-antipodal algorithm for finding the sink of an Acyclic Unique Sink Orientation on a cube

Auditor changes and tendering: UK interview evidence

Competitive pressures in the audit market have led to aggressive fee renegotiation and tendering by companies. This paper reviews microeconomic tender theory and finds it to be of limited value in the audit context. Content analysis of semi-structured interviews conducted with the finance directors of 12 UK listed companies which had recently tendered and/or changed auditor are used to investigate the tender/change process. Contrary to popular belief, fee levels do not necessarily dominate the decision to change auditors, rather changes within the client company, audit staffing, and auditor's professionalism and competency issues dominate. Nor is the selection of a tender "winner" generally based solely on price, as predicted by tender theory and as would be expected when the consequences of audit failure do not fall on the directors. However, consistent with economic theory, the winning bid appears frequently to be too low, resulting in attempts by auditors to subsequently increase fees and resentment by the finance director. Directors generally appear to view the audit tender as relating to not only the attest function per se, but to a larger package of services concerning the financial reporting function. The relative importance of price versus non-price competition in auditor choice is found to vary across companies. Auditor choice is influenced strongly by both economic and behavioural factors, in particular, by directors' assessment of the quality of non-attest services and the expected quality of working relationships, in addition to price and audit quality

Audit market competition: auditor changes and the impact of tendering

Increased competition within the external audit market and the recent phenomenon of audit tendering has renewed interest in the factors influencing auditor changes. In this paper, a questionnaire instrument is used to elicit perceptions of the factors which influence auditor-client realignments in this new environment and to indicate the relative influence of economic and behavioural factors. Positive, statistically significant associations were found between unsolicited approaches and the consideration of either a change in auditor or the conduct of a competitive tender. Fees are both the most frequently cited reason for considering auditor change and the most frequently cited factor influencing the selection of a new auditor. The chemistry of the relationship with senior audit firm personnel was ranked as more important than service issues in new auditor selection. Several significant associations between the reasons for change and both company size and type of change are identified. In particular, smaller companies, and companies changing from a non-Big Six firm, were more likely to change due to the need for a wider range of services and the influence of third parties. Findings indicated that 55% of auditor changes were effected by means of a tender, with the incumbent auditor having only an 18% chance of retaining the client. The various stages of the tender process appear to be dominated by the finance director, with audit committees having a restricted role. Tenders resulted in significant fee reductions in the year of change

Tests of an International Capital Asset Pricing Model with Stocks and Government Bonds and Regime Switching Prices of Risk and Intercepts

The paper tests a conditional multivariate International Capital Asset Pricing Model for US, Japanese and European stocks and government bonds, covering the period 1993-2001. Time variation in the prices of market and currency risk is modelled by means of synchronous regime switching. The paper also explores the statistical significance and time variation of asset specific intercept terms, again using synchronous regime switching. The prices of risk are found to be highly time varying. The price of market risk is statistically significant, and the international CAPM risk premia are validated, although currency risk premia are not statistically significant. However, the intercept terms are typically large and significant, implying an overall rejection of the international CAPM, and suggesting that additional, unidentified pricing factors contribute to return expectations.CAPM; Multivariate GARCH-in-Mean

Communication and support from health-care professionals to families, with dependent children, following the diagnosis of parental life-limiting illness : a systematic review

Background: Communication between parents and their children about parental life-limiting illness is stressful. Parents want support from health-care professionals; however, the extent of this support is not known. Awareness of family’s needs would help ensure appropriate support. Aim: To find the current literature exploring (1) how parents with a life-limiting illness, who have dependent children, perceive health-care professionals’ communication with them about the illness, diagnosis and treatments, including how social, practical and emotional support is offered to them and (2) how this contributes to the parents’ feelings of supporting their children. Design: A systematic literature review and narrative synthesis. Data sources: Embase, MEDLINE, PsycINFO, CINAHL and ASSIA ProQuest were searched in November 2015 for studies assessing communication between health-care professionals and parents about how to talk with their children about the parent’s illness. Results: There were 1342 records identified, five qualitative studies met the inclusion criteria (55 ill parents, 11 spouses/carers, 26 children and 16 health-care professionals). Parents wanted information from health-care professionals about how to talk to their children about the illness; this was not routinely offered. Children also want to talk with a health-care professional about their parents’ illness. Health-care professionals are concerned that conversations with parents and their children will be too difficult and time-consuming. Conclusion: Parents with a life-limiting illness want support from their health-care professionals about how to communicate with their children about the illness. Their children look to health-care professionals for information about their parent’s illness. Health-care professionals, have an important role but appear reluctant to address these concerns because of fears of insufficient time and expertise

Time and Parallelizability Results for Parity Games with Bounded Tree and DAG Width

Parity games are a much researched class of games in NP intersect CoNP that are not known to be in P. Consequently, researchers have considered specialised algorithms for the case where certain graph parameters are small. In this paper, we study parity games on graphs with bounded treewidth, and graphs with bounded DAG width. We show that parity games with bounded DAG width can be solved in O(n^(k+3) k^(k + 2) (d + 1)^(3k + 2)) time, where n, k, and d are the size, treewidth, and number of priorities in the parity game. This is an improvement over the previous best algorithm, given by Berwanger et al., which runs in n^O(k^2) time. We also show that, if a tree decomposition is provided, then parity games with bounded treewidth can be solved in O(n k^(k + 5) (d + 1)^(3k + 5)) time. This improves over previous best algorithm, given by Obdrzalek, which runs in O(n d^(2(k+1)^2)) time. Our techniques can also be adapted to show that the problem of solving parity games with bounded treewidth lies in the complexity class NC^2, which is the class of problems that can be efficiently parallelized. This is in stark contrast to the general parity game problem, which is known to be P-hard, and thus unlikely to be contained in NC

Auditor independence and audit risk: a reconceptualisation

The principles-based U.K. regulatory framework for auditor independence (Chartered Accountants Joint Ethics Committee 1996), which was adopted in 1997, identifies threats to independence in fact, independence in appearance, and the safeguards that control these threats. These principles are incorporated in the International Federation of Accountants (IFAC 2001) ethics framework. Drawing on six case studies of interactions involving significant accounting issues between audit engagement partners and finance directors in U.K.-listed companies, we analyze the threats and safeguards to auditor independence in fact that are relevant to the outcome of each interaction. Despite the U.K.'s comprehensive regulatory framework for independence, audit quality control, and independent inspection of firms, not all the interactions have a fully compliant outcome. Independence in fact is compromised where the safeguards in the framework are insufficient defense against the threats, particularly regarding intimidation and bullying during the audit process. Further examples of existing threats are identified and additional threats emerge, in particular an urgency threat, and a loss of face threat. Management motivation is found to be a key driver of pressure. Threats to independence arising within audit firms are not recognized in the current U.K. audit risk model. An extended risk model incorporating within-firm risk is suggested. This study demonstrates the need for continual improvement to regulatory frameworks; in particular it supports the recent U.S. Securities and Exchange Commission (SEC) rule on improper influence on the conduct of audits (Securities and Exchange Commission 2003a)

Briefing: Auditor/company interactions in the 2007 UK regulatory environment

No abstract availabl