https://neckpinch.com/authors/hamidreza-mahmoudian/New arXiv papers by Hamidreza Mahmoudian, from Neckpinch Tue, 03 Nov 2026 08:41:12 GMT https://neckpinch.com/papers/2311.12725/arxiv:2311.12725Tue, 21 Nov 2023 00:00:00 GMTHamidreza Mahmoudian — In this article we examine the formation of cylindrical neckpinch singularities in Ricci flow in compact manifolds. Rigorous examples of neckpinch sigularity for rotationally symmetric initial data were first constructed by Angenent and Knopf, and examples with given asymptotic behaviour were constructed by them and Isenberg. Here we discuss the asymptotic behavior of the flow under Type-I assumption for general symmetric initial data, and show the previously constructed asymptotic profiles and are the only possibilities.Ricci flowSingularitiesRotational symmetry & warped products https://neckpinch.com/papers/2311.09405/arxiv:2311.09405Wed, 15 Nov 2023 00:00:00 GMTZilu Ma, Hamidreza Mahmoudian, Natasa Sesum — In this paper we study 4d gradient steady Ricci solitons, which are weak κ-solutions, and admit O(3)-symmetry. Under a weak curvature decay condition, we find precise geometric asymptotics of such solitons, which are similar to those for 3d compact κ-solutions found in [ABDS22]. This is the first step towards the classification of 4d gradient steady Ricci solitons and more general ancient Ricci flows.Ricci flowRicci solitonsAncient solutions3-manifolds4-manifolds