arXiv subjects

Velibor Bojković

Publications and source records attributed to Velibor Bojković.

9 recordsLinked to original sources

arXiv2025

Temporal Misalignment in ANN-SNN Conversion and Its Mitigation via Probabilistic Spiking Neurons

Spiking Neural Networks (SNNs) offer a more energy-efficient alternative to Artificial Neural Networks (ANNs) by mimicking biological neural principles, establishing them as a promising approach to mitigate the increasing energy demands of large-scale neural models. However, fully harnessing the capabilities of SNNs remains challenging due to their discrete signal processing and temporal dynamics. ANN-SNN conversion has emerged as a practical approach, enabling SNNs to achieve competitive performance on complex machine learning tasks. In this work, we identify a phenomenon in the ANN-SNN conversion framework, termed temporal misalignment, in which random spike rearrangement across SNN layers leads to performance improvements. Based on this observation, we introduce biologically plausible two-phase probabilistic (TPP) spiking neurons, further enhancing the conversion process. We demonstrate the advantages of our proposed method both theoretically and empirically through comprehensive experiments on CIFAR-10/100, CIFAR10-DVS, and ImageNet across a variety of architectures, achieving state-of-the-art results.

cs.LG↗

arXiv2024

A note on rational surgeries on a Hopf link

It is clear that every rational surgery on a Hopf link in $3$-sphere is a lens space surgery. In this note we give an explicit computation which lens space is a resulting manifold. The main tool we use is the calculus of continued fractions. As a corollary, we recover the (well known) result on the criterion for when rational surgery on a Hopf link gives the $3$-sphere.

math.GT↗

arXiv2020

Optimal bases for direct images of $p$-adic differential modules over discs

Let $(k,|\cdot|)$ be a complete and algebraically closed valued field extension of $(\mathbb{Q}_p,|\cdot|_p)$. Given a finite morphism $φ:\mathscr{D}_1\to \mathscr{D}_2$ of unit discs over $k$, a differential module $(M,D)$ on $\mathscr{D}_1$ and a point $b\in \mathscr{D}_2(k)$, we construct explicitly an optimal basis of space of horizontal elements for the direct image $φ_*(M,D)$ at $b$ in terms of the suitable chosen optimal bases of $(M,D)$ at preimages of $b$ by $φ$ and ramification properties of the morphism.

math.NT↗

arXiv2019

Canonical factorizations of morphisms of Berkovich curves

We prove that, for certain extensions of valued fields which admit a sensible theory of ramification groups, there exist canonical towers that correspond to the break-points of their Herbrand function. In particular, each of the intermediate field extensions in the tower has a Herbrand function with only one break-point and there is at most one extension with trivial Herbrand function. We apply the result to the setting of finite morphisms of Berkovich curves where we prove the existence of canonical local and global factorization of such morphisms according to their metric properties. Finally, we use the canonical factorizations to prove harmonicity properties finite morphisms satisfy at each type 2 point: formulas that can be regarded as a refinement of the Riemann-Hurwitz formula for such morphisms.

math.AG↗

arXiv2019

Metric uniformization of morphisms of Berkovich curves via $p$-adic differential equations

We consider a finite étale morphism $f:Y \to X$ of quasi-smooth Berkovich curves over a complete nonarchimedean non-trivially valued field $k$, assumed algebraically closed and of characteristic 0, and a skeleton $Γ_f=(Γ_Y,Γ_X)$ of the morphism $f$. We prove that $Γ_f$ radializes $f$ if and only if $Γ_X$ controls the pushforward of the constant $p$-adic differential equation $f_*(\mathcal{O}_Y,d_Y)$. Furthermore, when $f$ is a finite étale morphism of open unit discs, we prove that $f$ is radial if and only if the number of preimages of a point $x\in X$, counted without multiplicity, only depends on the radius of the point $x$.

math.AG↗

arXiv2019

Mittag-Leffler problems on Berkovich curves

Given a quasi-smooth Berkovich curve $X$ admitting a finite triangulation, finitely many disjoint open annuli $A_1,\dots,A_n$ in $X$ that are not precompact, and for each $i=1,\dots, n$, an analytic function $f_i$ (resp. differential form $σ_i$) convergent on $A_i$, we provide a criterion for when there exists an analytic function $f$ (resp. a differential form $σ$) on $X$ inducing the functions $f_i$ (resp. differentials $σ_i$). Along the way we reprove residue theorem for differentials on smooth Berkovich curves that admit finite triangulations.

math.AG↗

arXiv2018

Pushforwards of $p$-adic differential equations

Given a differential equation on a smooth $p$-adic analytic curve, one may construct a new one by pushing forward by an étale morphism. The main result of the paper provides an explicit formula that relates the radii of convergence of the solutions of the two differential equations using invariants coming from the topological behavior of the morphism. We recover as particular cases the known formulas for Frobenius morphisms and tame morphisms. As an application, we show that the radii of convergence of the pushforward of the trivial differential equation at a point coincide with the upper ramification jumps of the extension of the residue field of the point given by the morphism. We also derive a general formula computing the Laplacian of the height of the Newton polygon of a $p$-adic differential equation.

math.NT↗

arXiv2018

On the number of connected components of the ramification locus of a morphism of Berkovich curves

Let $k$ be a complete, nontrivially valued non-archimedean field. Given a finite morphism of quasi-smooth $k$-analytic curves that admit finite triangulations, we provide upper bounds for the number of connected components of the ramification locus in terms of topological invariants of the source curve such as its topological genus, the number of points in the boundary and the number of open ends.

math.AG↗

arXiv2017

Riemann-Hurwitz formula for finite morphisms of $p$-adic curves

Given a finite morphism $φ:Y\to X$ of quasi-smooth Berkovich curves over a complete, algebraically closed field $k$ of characteristic $0$, we prove a Riemann-Hurwitz formula relating their Euler-Poincaré characteristics (calculated using De Rham cohomology of their overconvergent structure sheaf). The main tools are $p$-adic Runge's theorem together with valuation polygons of analytic functions. Using the results obtained, we provide another point of view on Riemann-Hurwitz formula for finite morphisms of curves over algebraically closed fields of positive characteristic.

math.AG↗