Conformant Planning as a Case Study of Incremental QBF Solving

We consider planning with uncertainty in the initial state as a case study of incremental quantified Boolean formula (QBF) solving. We report on experiments with a workflow to incrementally encode a planning instance into a sequence of QBFs. To solve this sequence of incrementally constructed QBFs, we use our general-purpose incremental QBF solver DepQBF. Since the generated QBFs have many clauses and variables in common, our approach avoids redundancy both in the encoding phase and in the solving phase. Experimental results show that incremental QBF solving outperforms non-incremental QBF solving. Our results are the first empirical study of incremental QBF solving in the context of planning and motivate its use in other application domains.Comment: added reference to extended journal article; revision (camera-ready, to appear in the proceedings of AISC 2014, volume 8884 of LNAI, Springer

SAT-Based Methods for Circuit Synthesis

Reactive synthesis supports designers by automatically constructing correct hardware from declarative specifications. Synthesis algorithms usually compute a strategy, and then construct a circuit that implements it. In this work, we study SAT- and QBF-based methods for the second step, i.e., computing circuits from strategies. This includes methods based on QBF-certification, interpolation, and computational learning. We present optimizations, efficient implementations, and experimental results for synthesis from safety specifications, where we outperform BDDs both regarding execution time and circuit size. This is an extended version of [2], with an additional appendix.Comment: Extended version of a paper at FMCAD'1

The Impact of Securitization, Bank Liquidity Shocks, and Government Intervention on Lending and Banks\u27 Asset Composition: Evidence from The U.S. 2007-2009 Financial Crisis

The 2007- 2009 financial crisis creates a new wave of research opportunities in part due to the transformation of the banking system that led to the development of securitized banking that is supported by short term funding sources provided through the money and capital markets. The near collapse of the financial system ultimately led to the ensuing government intervention by the Federal Reserve and the U.S. Treasury department to revive the frail U.S. economy. This dissertation has two basic research objectives: 1) investigate the impact of securitization and the subprime mortgage collapse on bank lending during the crisis and 2) examine changes in banks’ balance sheet composition associated with government intervention. Results suggest that traditional bank funding costs play a diminished role in the supply of bank lending in the larger bank samples (large banks and money center banks) and yet there is a positive impact of the repurchase agreement (REPO) market rates on bank lending that is pervasive in the smaller bank samples (small and medium) suggesting that increases in Repo rates fosters lending during the crisis period. Real estate lending exposure negatively affects bank lending in the small and medium bank samples. The evidence suggests that the Federal Reserves initial round of quantitative easing served as an important channel through which banks were able to attain liquidity objectives during the crisis. The results suggest that small and money center banks with greater loan portfolio exposures choose to build liquidity in response to a rise in Repo rates compared to banks with lower lending exposures. Finally, the balance sheet composition for banks in general has shifted towards more liquid based banks in the post crisis period and residential real estate portfolios has reverted to pre-crisis levels for money center banks and has remained mostly consistent throughout the sample period for all other banks with a modest rise noted in the post crisis period for large banks

Trading Income and Bank Charter Value during the Financial Crisis: Does Derivatives Dealer Designation Matter?

Derivative markets have exploded over the last decade, remained active in the midst of the 2007-2009 financial crises and continue to be dominated by a small group of bank holding companies (BHC). BHC motives for derivative usage are usually tied to hedging purposes (balance sheet risk management), trading purposes (profit motives) or some combination thereof. This paper examines the relationship between derivative trading income and bank charter value for 27 BHC between 2001Q1-2011Q3. We find that the impact of derivative trading income on bank charter value, using Tobin’s Q, is very small and seems to be tied to BHCs derivatives dealer trading designation. We also find that trading incomes are a modest fraction of net operating revenue, highly volatile, and did not contribute to overall BHC income during the crisis

A coordinated phosphorylation cascade initiated by MSK1 directs RAR alpha recruitment to target gene promoters

The nuclear retinoic acid (RA) receptor alpha (RARα) is a transcriptional transregulator that controls the expression of specific gene subsets through binding at response elements and dynamic interactions with coregulators, which are coordinated by the ligand. Here, we highlighted a novel paradigm in which the transcription of RARα-target genes is controlled by phosphorylation cascades initiated by the rapid RA activation of the p38MAPK/MSK1 pathway. We demonstrate that MSK1 phosphorylates RARα at S369 located in the Ligand Binding Domain, allowing the binding of TFIIH and thereby phosphorylation of the N-terminal domain at S77 by cdk7/cyclin H. MSK1 also phosphorylates Histone H3 at S10. Finally, the phosphorylation cascade initiated by MSK1 is required for the recruitment of RARα/TFIIH complexes to response elements and subsequently for RARα target genes activation. Cancer cells characterized by a deregulated p38MAPK/MSK1 pathway, do not respond to RA, outlining the essential contribution of the RA-triggered phosphorylation cascade in RA signaling