Audit Games with Multiple Defender Resources

Modern organizations (e.g., hospitals, social networks, government agencies) rely heavily on audit to detect and punish insiders who inappropriately access and disclose confidential information. Recent work on audit games models the strategic interaction between an auditor with a single audit resource and auditees as a Stackelberg game, augmenting associated well-studied security games with a configurable punishment parameter. We significantly generalize this audit game model to account for multiple audit resources where each resource is restricted to audit a subset of all potential violations, thus enabling application to practical auditing scenarios. We provide an FPTAS that computes an approximately optimal solution to the resulting non-convex optimization problem. The main technical novelty is in the design and correctness proof of an optimization transformation that enables the construction of this FPTAS. In addition, we experimentally demonstrate that this transformation significantly speeds up computation of solutions for a class of audit games and security games

Использование игровых методов в процессе изучения бухгалтерского учета и аудита

The point of view on the use of business games at studying such subject matters as accounting and audit has been expressed In this article. It is said, that business games promote increase of efficiency and quality of economic education as they allow to create more comfortable conditions for development of creative abilities of the future specialists, of their individuality and independence in comparison to traditional trainin

Iowa Lottery Authority, Independent Auditor's Reports, Basic Financial Statements and Supplementary Information, Schedule of Findings, June 30, 2006

State Audit Report

Adaptive Regret Minimization in Bounded-Memory Games

Online learning algorithms that minimize regret provide strong guarantees in situations that involve repeatedly making decisions in an uncertain environment, e.g. a driver deciding what route to drive to work every day. While regret minimization has been extensively studied in repeated games, we study regret minimization for a richer class of games called bounded memory games. In each round of a two-player bounded memory-m game, both players simultaneously play an action, observe an outcome and receive a reward. The reward may depend on the last m outcomes as well as the actions of the players in the current round. The standard notion of regret for repeated games is no longer suitable because actions and rewards can depend on the history of play. To account for this generality, we introduce the notion of k-adaptive regret, which compares the reward obtained by playing actions prescribed by the algorithm against a hypothetical k-adaptive adversary with the reward obtained by the best expert in hindsight against the same adversary. Roughly, a hypothetical k-adaptive adversary adapts her strategy to the defender's actions exactly as the real adversary would within each window of k rounds. Our definition is parametrized by a set of experts, which can include both fixed and adaptive defender strategies. We investigate the inherent complexity of and design algorithms for adaptive regret minimization in bounded memory games of perfect and imperfect information. We prove a hardness result showing that, with imperfect information, any k-adaptive regret minimizing algorithm (with fixed strategies as experts) must be inefficient unless NP=RP even when playing against an oblivious adversary. In contrast, for bounded memory games of perfect and imperfect information we present approximate 0-adaptive regret minimization algorithms against an oblivious adversary running in time n^{O(1)}.Comment: Full Version. GameSec 2013 (Invited Paper

The importance of reputation in the auditing of companies: A game theory analysis

Numerous, mainly empirical, studies of auditing behaviour have recently looked at the “reputation” of the auditor and the size of fees it attracts. Our model of the auditing market advances the study of the fundamental principles involved in determining behaviour in relation to the rewards and penalties using an extensive-form game of the auditing process. We set up a two-player fraud detection game with bribes, bonuses and fines faced by an auditor. Our model yields that the auditor’s reputation, reflected in the size of bonuses, is critical to establishing a non-fraudulent behaviour by the client. Hence the model confirms expected behaviour. We further find the new insight, that while the existence of penalties deters fraud by the client, their size is not critical. This is a new understanding of what determines auditor behaviour. It is the perception of a possible penalty that moves the auditor in the direction of executing a thorough investigation using his acquired expertise

Impact of the introduction of machine gaming in Queensland on minor and major bingo

Material for this paper comes from as report commissioned by the Department of Family Services, Aboriginal and Islander Affairs. The report is the result of a multi strategy research project designed to assess the impact of gaming machines on the fundraising capacity of charitable and community organisations in Queensland. The study was conducted during the 1993 calendar year. The first Queensland gaming machine was commissioned on the 11 February, 1992 at 11.30 am in Brisbane at the Kedron Wavell Services Club. Eighteen more clubs followed that week. Six months later there were gaming machines in 335 clubs, and 250 hotels and taverns, representing a state wide total of 7,974 machines in operation. The 10,000 gaming machine was commissioned on the 18 March, 1993 and the 1,000 operational gaming machine site was opened on 18th February, 1994

Mixed Strategies in Simultaneous and Sequential Play of a 2 Player Game

We take a class of games with two players and two actions which only have mixed strategy Nash equilibria. We show that such games can only have hybrid equilibria if played sequentially with one player moving first. The hybrid equilibrium has the leader p laying a mixed strategy but the follower playing a pure strategy. We apply this result to a game between a debtor and a lender following a loan contract. The debtor can have high or low revenues and has to report his state to the lender. The lender can choose whether or not to undertake a costly audit. With simultaneou s play there is only a mixed strategy Nash equilibrium with random cheating in reports and auditing. With sequential play if the debtor moves first, there is zero auditing and the debtor cheats as much as possible without giving the incentive to audit. We argue that the setting of the game and the valuable first mover advantage of the debtor mean that we should expect the game to be played sequentially with this hybrid outcome. This is important in the context of the loan contract since the hybrid outcome makes the contract renegotiation proof. Alternatively if the timing allowed the lender to move first, then the equilibrium would have the debtor reporting truthfully and the monitor auditing just sufficiently to ensure truthtelling by the debtor. This ha s strong links to the optimal debt contract with no commitment (Mookherjee-Png, 1989 and Jost, 1996). However we argue that the natural timing of events makes the debtor the leader. We then consider other examples and show that the same outcome emerges in matching pennies and in a generic inspection game involving adverse selection in labour markets.Mixed Strategies; Loan Contracts; First Mover Advantage