Publications by Year: Submitted

A LAnKe (also known as a Lie algebra of the th kind, or a Filippov algebra) is a vector space equipped with a skew-symmetric -linear form that satisfies the generalized Jacobi identity. The symmetric group  acts on the multilinear part of the free LAnKe on  generators, where  is the number of brackets, by permutation of the generators. The corresponding representation was studied by Friedmann, Hanlon, Stanley and Wachs, who asked whether for , its irreducible decomposition contains no summand whose Young diagram has at most  columns. The answer is affirmative if $k \le 3$. In this paper, we show that the answer is affirmative for all $k$

We analyze the impact of the institutional environment on the leverage of European listed SMEs for the period 2005-2018. We use a broad range of institutional quality, judicial efficiency and corruption measures, along with several firm-specific and macro control variables, to identify different transmission channels on leverage. By performing a panel data analysis into the fixed effects filter estimator framework, along with several model specifications and robustness tests, the results show that better institutions, stronger judicial effectiveness and higher corruption decrease leverage. In terms of active transmission channels, increased investment under regimes of better institutional quality tends to increase leverage. Higher judicial efficiency accompanied by increased profitability tends to decrease, while higher institutional quality accompanied by higher investments tends to increase leverage, bringing more bank credit. Increasing profitability under regimes of decreased corruption decreases leverage. This last finding is even more pronounced for medium enterprises, as opposed to micro enterprises. The most significant factors associated with leverage are profitability, asset structure, cost of borrowing, stock market development and size, while an age effect is rejected. Pecking order theory seems to better fit the European SMEs capital structure choices under several institutional states.

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Given a filtration of the module of vector fields on a smooth manifold, we define a pseudodifferential calculus where the order of a vector field is given by the filtration. We show that pseudodifferential operators have a well-defined principal symbol for a subset of the unitary representations of the osculating groups. We prove a Rockland-type theorem, showing that the invertibility of the principal symbol is equivalent to maximal hypoellipticity. This answers affirmatively a conjecture due to Helffer and Nourrigat.

Loneliness during adolescence has increased worldwide in recent years and has been consistently associated with a broad range of adverse psychosocial outcomes. Within this context, the availability of valid and reliable measures is essential for the early identification of loneliness and for the rigorous evaluation of intervention effectiveness. Nevertheless, multidimensional, psychometrically validated instruments for assessing loneliness in Greek adolescents remain limited. The aim of the present study was to examine the psychometric properties of the Greek version of the Relational Provisions Loneliness Questionnaire (RPLQ; Hayden-Thomson, 1989), which assesses social and emotional dimensions of loneliness (i.e., integration and intimacy) within the primary relational contexts of family and peer relationships. The sample consisted of 503 students aged 13–14 years, selected via stratified random sampling. Confirmatory factor analysis supported the four-factor model, which demonstrated the best fit to the data and yielded high standardized factor loadings. Internal consistency indices were high across all dimensions, and convergent, discriminant, and concurrent validity were supported. Measurement invariance across gender was also supported at the configural, metric, and scalar (threshold) levels. Overall, the findings indicate that the Greek version of the RPLQ is a valid and reliable instrument for the assessment of adolescent loneliness.

We extend Grood's tableau construction of irreducible representations of the rook monoid and Steinberg's analogous result for the full transformation monoid. Our approach is characteristic-free and applies to any submonoid \mathcal{M}(n) of the partial transformation monoid on an n-element set that contains the symmetric group. To achieve this, we introduce and study a functor from the category of rational representations of the monoid of n \times n matrices to the category of finite dimensional representations of \mathcal{M}(n). We establish two branching rules. Our main results describe graded module structures of orbit harmonics quotients for the rook, partial transformation, and full transformation monoids. This yields analogs of the Cauchy decomposition for polynomial rings in n\times n variables.