This paper presents a robust bi-level co-optimization model that promotes the active participation of Internet Data Centers (IDCs) in demand response (DR) programs, thereby enhancing the flexibility of power systems. Our approach involves leveraging virtual power lines to migrate workloads among IDCs, optimizing resource allocations, and benefiting both domains. The model incorporates a Gaussian Process Regression (GPR)-constructed DR price–amount curve, which largely contributes to the simplification of the optimization problem with high accuracy and computational efficiency. It also respects the information barriers between the two domains of power systems and IDCs, and thus safeguards the privacy and flexibility of IDCs. The uncertainty in IDC operations is considered by incorporating the variance in GPR into the demand response curve. By integrating IDCs as DR resources, the framework of this research enhances the flexibility of power systems and the efficiency of cross-domain co-optimization. The model and algorithm are validated using modified IEEE test systems.

Theoretical basis This case covers the framework and process to determine fair value as specified in International Financial Reporting Standards (IFRS) 13. It illustrates an instance in which auditors interpret the concept of fair value to be consistent with other principles in standards such as the principle of prudence in the conceptual framework. In addition, a lot of the discussion in the case is applicable to accounting education in any regulatory jurisdictions given the convergence of US generally accepted accounting principles (GAAP) and IFRS 13. In addition, while fair value accounting may have been designed to give investors more useful information, in practise it could involve highly subjective judgement and the resulting implementation may be affected by incentives of different stakeholders. The CK Tang’s case provides an excellent opportunity to discuss incentives of varies parties in determining the fair value in financial reporting decisions. In short, this case could be a good jumping-off point to talk about management and auditors’ incentives in financial reporting in general. Research methodology Publicly available information (e.g. financial reporting standards, corporate announcements and reports, news reports) was used as the basis for this case. Case overview/synopsis The case centres on an iconic Singaporean integrated retailing and property landlord entity: Tang holdings. As part of its succession planning, the company’s founding family decided to take its listing arm, C.K. Tang Limited (CK Tang hereafter), private in May 2006. The Tang brothers, who represented the controlling family, initiated several attempts to delist the company. The minority shareholders of CK Tang were unhappy that the offer price was below the net asset value of the company. The minority shareholders also highlighted that the reported fair value of the flagship Tang Plaza complex understated its highest and best use and might not possibly comply with International Financial Reporting Standards (IFRS) 13. Complexity academic level The case can be used for class discussions with undergraduate students or master students in intermediate accounting courses.