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Yann Sepulcre

Publications and source records attributed to Yann Sepulcre.

3 recordsLinked to original sources

Doubly Stochastic Mean-Shift Clustering

Standard Mean-Shift algorithms are notoriously sensitive to the bandwidth hyperparameter, particularly in data-scarce regimes where fixed-scale density estimation leads to fragmentation and spurious modes. In this paper, we propose Doubly Stochastic Mean-Shift (DSMS), a novel extension that introduces randomness not only in the trajectory updates but also in the kernel bandwidth itself. By drawing both the data samples and the radius from a continuous uniform distribution at each iteration, DSMS effectively performs a better exploration of the density landscape. We show that this randomized bandwidth policy acts as an implicit regularization mechanism, and provide convergence theoretical results. Comparative experiments on synthetic Gaussian mixtures reveal that DSMS significantly outperforms standard and stochastic Mean-Shift baselines, exhibiting remarkable stability and preventing over-segmentation in sparse clustering scenarios without other performance degradation.

cs.LG

Stochastic Mean-Shift Clustering

We present a stochastic version of the mean-shift clustering algorithm. In this stochastic version a randomly chosen sequence of data points move according to partial gradient ascent steps of the objective function. Theoretical results illustrating the convergence of the proposed approach, and its relative performances is evaluated on synthesized 2-dimensional samples generated by a Gaussian mixture distribution and compared with state-of-the-art methods. It can be observed that in most cases the stochastic mean-shift clustering outperforms the standard mean-shift. We also illustrate as a practical application the use of the presented method for speaker clustering.

cs.LG

Le degre de la variete des courbes de Poncelet

We compute the degree of the projective variety of Poncelet curves of degree $n$. This variety is irreducible of dimension $2 n + 5$, and lies inside the projective space of degree $n$ plane curves. It is classically defined as the closure on this projective space of the locally closed subset of curves passing through the vertices of some nondegenerate $n$ sided polygone inscribed in some smooth conic (the polygone and the conic being variable). It is related to a specific class of semi-stable sheaves on the projective (dual) plane, named Poncelet sheaves. Using moduli spaces birational to the variety of Poncelet curves, we compute the requested degree. It involves quite cumbersome computations, and we obtain general formulas for $n \geq 4$. We do numerical applications for $n \leq 6$. For $n=4$ we find back the well known Donaldson number of the projective plane, 54, which is the degree of the hypersurface of Luroth quartics.

math.AG