arXiv subjects

Dragos Deliu

Publications and source records attributed to Dragos Deliu.

4 recordsLinked to original sources

arXiv2022

BiRank vs PageRank: Using SNA on Company Register Data for Fiscal Risk Prediction

Efficient financial administrations need to ensure compliant behavior of all tax subjects without excessive personnel costs or obstruction of compliant companies. To do so, accurate prediction of non-compliance or fraud is crucial. Social Network Analysis (SNA) provides powerful tools for fraud prediction as fraudulence is often clustered in certain areas of real world social networks. In this paper we present our results of comparing PageRank and the more recent BiRank to infer risk-ranks based on network structure and prior fraud information. Specifically, we model our social network from company register data. We find that in this case study BiRank outperforms PageRank in both quality of the resulting ranks for fraud prediction and run time. The results show that this class of algorithms is generally useful for fraud and risk prediction and more specifically also illustrate the potential of BiRank in comparison, as it opens up new modeling opportunities. Our results show that selecting companies for tax audits based on BiRank yields a precision of 16.38% for the top 20.000 subjects selecting 83.4% of all fraud cases (recall).

cs.SI↗

arXiv2014

Homological Projective Duality via Variation of Geometric Invariant Theory Quotients

We provide a geometric approach to constructing Lefschetz collections and Landau-Ginzburg Homological Projective Duals from a variation of Geometric Invariant Theory quotients. This approach yields homological projective duals for Veronese embeddings in the setting of Landau Ginzburg models. Our results also extend to a relative Homological Projective Duality framework.

math.AG↗

arXiv2014

On the Derived Categories of Degree d Hypersurface Fibrations

We provide descriptions of the derived categories of degree $d$ hypersurface fibrations which generalize a result of Kuznetsov for quadric fibrations and give a relative version of a well-known theorem of Orlov. Using a local generator and Morita theory, we re-interpret the resulting matrix factorization category as a derived-equivalent sheaf of dg-algebras on the base. Then, applying homological perturbation methods, we obtain a sheaf of $A_\infty$-algebras which gives a new description of homological projective duals for (relative) $d$-Veronese embeddings, recovering the sheaf of Clifford algebras obtained by Kuznetsov in the case when $d=2$.

math.AG↗

arXiv2014

Resolutions in factorization categories

Generalizing Eisenbud's matrix factorizations, we define factorization categories. Following work of Positselski, we define their associated derived categories. We construct specific resolutions of factorizations built from a choice of resolutions of their components. We use these resolutions to lift fully-faithfulness statements from derived categories of Abelian categories to derived categories of factorizations and to construct a spectral sequence computing the morphism spaces in the derived categories of factorizations from Ext-groups of their components in the underlying Abelian category.

math.CT↗