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INFORMS Nashville – 2016

316

4 - Influence Maximization In Linear Threshold And Triggering Models

Po-Ling Loh, UW - Madison, Madison, WI, 53717, United States,

polingloh@gmail.com

We discuss upper and lower bounds for the influence of a set of nodes in certain

types of contagion models. We quantify the gap between our upper and lower

bounds in the case of the linear threshold model and illustrate the gains of our

upper bounds for independent cascade models in relation to existing results.

Furthermore, our lower bounds are monotonic and submodular, implying that a

greedy algorithm for influence maximization is guaranteed to produce a

maximizer within a $\left(1-\frac{1}{e}\right)$-factor of the truth. Our bounds

may be evaluated efficiently, leading to an attractive, highly scalable algorithm for

influence maximization with rigorous theoretical guarantees.

TC41

207C-MCC

Quantitative Risk Management

Sponsored: Financial Services

Sponsored Session

Chair: Abel Cadenillas, University of Alberta, Edmonton, AB, Canada,

abel@ualberta.ca

1 - Systemic Influences On Optimal Equity-credit Investment

Christoph Frei, University of Alberta,

cfrei@ualberta.ca,

Agostino Capponi

Recent events showed that the dependence structure of financial markets is more

complex than what is captured by classical models. For example, the financial

instability of some companies spread out to affect other companies. We analyze

how such systemic influences are reflected in optimal investment decisions. To

this end, we introduce a model with dependence structure between market risk

and default risk of the companies. An investor can use stocks and credit default

swaps (CDSs) to participate in the market. We derive an explicit expression for

the optimal investment strategy in stocks and CDSs. An empirical analysis reveals

the critical role of systemic risk in portfolio monitoring.

2 - Optimal Governement Debt Ceiling

Abel Cadenillas, University of Alberta,

abel@ualberta.ca,

Ricardo Huaman-Aguilar

Motivated by the debt crisis in the world, we apply methods of stochastic control

to obtain an explicit formula for the optimal government debt ceiling.

3 - Optimal Cash Holdings Under Funding Risk

Andreea Minca, Cornell University,

acm299@cornell.edu

This talk explores a one-period model for a firm that finances itsoperations

through debt provided by heterogeneous creditors. Creditorsdiffer in their beliefs

about the firm’s investment outcomes. We showthe existence of Stackelberg

equilibria in which the firm holds cashreserves in order to provide incentives for

pessimistic creditorsto invest in the firm. We find interest rates and cash holdings

tobe complementary tools for increasing debt capacity. In markets witha high

concentration of capital across a small interval of pessimisticcreditors or by a few

large creditors, cash holdings is the preferredtool to increase the debt capacity of

the firm.

4 - EM Algorithm and Stochastic Control

Steven Kou, National University of Singapore,

matsteve@nus.edu.sg

We propose an algorithm called EM-Control (EM-C) algorithm to solve multi-

period finite-time horizon stochastic control problems. Generalizing the idea of

the EM algorithm, the EM-C algorithm sequentially updates the control parame-

ters in each time period in a backward manner. The EM-C algorithm has monot-

onicity of performance improvement in every iteration. We apply the EM-C algo-

rithm to solve stochastic control problems in real business cycle and monopoly

pricing of airline tickets. This is a joint work with Xianhua Peng and Xingbo Xu.

TC42

207D-MCC

Revenue Management with Advertising Applications

Sponsored: Revenue Management & Pricing

Sponsored Session

Chair: John G Turner, University of California - Irvine, Room SB2 338,

Irvine, CA, 92697-3125, United States,

john.turner@uci.edu

1 - The Bid Adjustment Problem In Search Advertising

Mustafa Sahin, University of Maryland,

mustafa.sahin@rhsmith.umd.edu

, Subramanian Raghavan,

Abhishek Pani, Abhishek Pani

We discuss the problem faced by the advertiser in search advertising in the

presence of bid adjustments. Recent developments in search advertising created a

setting in which the advertiser can target specific demographics by using bid

adjustments. We propose a Mixed Integer Programming formulation for the

problem. However, the problem is computationally hard and cannot be solved by

a generic commercial solver for any instance of reasonable size. Therefore, we

offer heuristic approaches to tackle the intractability issues and present results on

hard instances.

2 - Analysis Of Competitive Pricing With Multiple Overlapping

Competing Bids In Revenue Management

Goutam Dutta, Professor, Indian Institute of Management, House

No 407, Iima Old Campus, Vastrapur, Ahmedabad, 380015, India,

goutam@iima.ac.in

We formulate the pricing problem from the point of view of one seller having one

or multiple competitors (say n). Based on past experience, we know the

distribution of bid prices of the competitors. We consider uniform and normal

distribution to describe the bid price of the competitors. The prices of the

competitors are mutually independent and the price ranges are either identical or

different and overlapping. We maximize the expected contribution of the seller.

Assuming the contribution as a linear function of price we find the conditions for

maximization of the expected contribution to profit in case of n bidders. Further,

we also compare the optimization results with simulation results.

3 - Markov Chain Models For Controlling The Frequency Distribution

Of Online Advertising

Seyed Ali Hojjat, University of New Hampshire, Durham, NH,

United States,

ali.hojjat@unh.edu,

John G Turner

Recent trends in online advertising show that explicit reach and frequency

specifications are more desired over aggregate impression or budget goals.

Depending on whether the frequency of ad serving to each user is measured over

a fixed timespan (e.g., the number of times each user is exposed to the ad within

each calendar week) or on a rolling basis (e.g., over any contiguous 24-hour

period throughout the campaign’s horizon), we propose an appropriate Markov

chain model for serving ads and investigate its properties in maintaining a desired

frequency distribution for an online ad campaign.

4 - Planning Online Advertising Using Lorenz Curves

John G Turner, University of California - Irvine, Irvine, CA,

United States,

john.turner@uci.edu

, Miguel A Lejeune

Lorenz curves are commonly-used to depict dispersion; e.g., income inequality.

Motivated by online advertising campaigns that desire impressions spread over

targeted audience segments and time, we formulate a problem that minimizes

Gini Coefficients (area under the Lorenz curve), and develop a specialized

decomposition technique to solve instances quickly.

TC43

208A-MCC

Decision Making in Public Policy

Sponsored: Decision Analysis

Sponsored Session

Chair: Cameron MacKenzie, Iowa State University, Ames, IA,

United States,

camacken@iastate.edu

1 - Hurricane Decision Simulator

Eva D Regnier, Naval Postgraduate School,

eregnier@nps.edu

,

Cameron MacKenzie, Eric S Hodson

When threatened by a hurricane, Marines in New Orleans face a classic sequential

decision under uncertainty with regularly updated information, but few

opportunities to learn from experience. The Hurricane Decision Simulator allows

personnel to run experience key decisions in the context of many realistic

simulated storms, to develop a better understanding of the interrelated decisions

required, and a familiarity with the forecast products and their evolving

uncertainty. This talk highlights application of both “hard” and “soft” sides of

analytics in the development of the tool. This is the first hurricane training tool

that allows users to explore many different decision paths.

2 - Subsidizing Cybersecurity Information Sharing: A Game Between

A Government And N-Companies

Ali Pala, University at Buffalo, Buffalo, NY, 14260, United States,

alipala@buffalo.edu

Ali Pala, Turkish Military Academy, Devlet Mahallesi, Bakanlıklar,

Ankara, Turkey,

alipala@buffalo.edu

, Jun Zhuang

More cybersecurity information sharing would lead to stronger resistance against

cyber-attacks in the presence of a cooperative and trustworthy sharing network.

Sharing cyber-attack information, however, could harm reputation, create

disadvantages against competitors and additional costs, and cause disclosing

vulnerabilities and some private information. In this research, we study what,

how, and to whom government incentives should be provided in order to

encourage and improve information sharing. We incorporate game theory and

agent-based simulation modeling to develop a dynamic decision support tool that

generates information sharing strategies in the face of strategic attackers.

TC41