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Special generic maps are higher dimensional versions of Morse functions with exactly two singular points, characterizing spheres topologically except $4$-dimensional cases: in these cases standard spheres are characterized. Canonical…

Algebraic Topology · Mathematics 2022-04-12 Naoki Kitazawa

Morse functions with exactly two singular points on spheres and canonical projections of spheres belong to the class of a certain good class of smooth maps: special generic maps. We mainly investigate information on cohomology of closed and…

Algebraic Topology · Mathematics 2022-09-13 Naoki Kitazawa

The canonical projections of the unit spheres are generalized to special generic maps and round fold maps, for example. They are generalizations from the viewpoint of singularity theory of differentiable maps and these maps restrict the…

Algebraic Geometry · Mathematics 2026-02-13 Naoki Kitazawa

Morse functions with exactly two singular points on homotopy spheres and canonical projections of spheres are generalized as special generic maps. A special generic map is, roughly, a smooth map represented as the composition of a smooth…

Algebraic Geometry · Mathematics 2025-03-28 Naoki Kitazawa

In our paper, we introduce special-generic-like maps or SGL maps as smooth maps and study their several algebraic topological and differential topological properties. The new class generalize the class of so-called special generic maps.…

General Topology · Mathematics 2023-02-14 Naoki Kitazawa

As a higher dimensional version of the theory of Morse functions, there have been various studies of smooth manifolds using generic smooth maps. As fundamental results, in these studies, they have found that inverse images of such maps…

Algebraic Topology · Mathematics 2018-12-21 Naoki Kitazawa

We present new explicit decompositions of manifolds via so-called fold maps into lower dimensional spaces. Fold maps form a nice class of so-called generic maps, generalizing Morse functions naturally. To understand the topologies and the…

General Topology · Mathematics 2022-11-28 Naoki Kitazawa

There are two rather distinct approaches to Morse theory nowadays: smooth and discrete. We propose to study a real valued function by assembling all associated sections in a topological category. From this point of view, Reeb functions on…

Algebraic Topology · Mathematics 2021-09-14 Paul Trygsland

Classes of branched surfaces extend the classes of surfaces or 2-dimensional manifolds satisfying suitable properties and defined in various manners. Reeb spaces of smooth maps of suitable classes into surfaces whose codimensions are…

General Topology · Mathematics 2022-08-16 Naoki Kitazawa

A special generic map is a smooth map regarded as a natural generalization of Morse functions with just 2 singular points on homotopy spheres. Canonical projections of unit spheres are simplest examples of such maps and manifolds admitting…

Geometric Topology · Mathematics 2018-11-30 Naoki Kitazawa

We have been interested in understanding the class of 7-dimensional closed and simply-connected manifolds in geometric and constructive ways. We have constructed explicit fold maps, which are higher dimensional versions of Morse functions,…

Algebraic Topology · Mathematics 2022-04-11 Naoki Kitazawa

We study cobordisms of a class of topological operads called ``manifold operads''. These operads are generalizations of the Fulton-MacPherson operad: an operad built from configurations of points in Euclidean space. Cobordism of manifold…

Algebraic Topology · Mathematics 2026-05-14 Xujia Chen , Connor Malin , Paolo Salvatore

7-dimensional closed and simply-connected manifolds have been attractive as central and explicit objects in algebraic topology and differential topology of higher dimensional closed and simply-connected manifolds, which were studied…

Algebraic Topology · Mathematics 2021-02-16 Naoki Kitazawa

We connect topological changes that can occur in $3$-space via surgery, with black hole formation, the formation of wormholes and new generalizations of these phenomena, including relationships between quantum entanglement and wormhole…

Geometric Topology · Mathematics 2018-12-04 Stathis Antoniou , Louis H. Kauffman , Sofia Lambropoulou

Reeb spaces of smooth functions are fundamental and strong tools in understanding manifolds via smooth functions with mild critical points. They are defined as the natural spaces of all connected components of level sets. They are also…

General Mathematics · Mathematics 2026-03-04 Naoki Kitazawa

In our paper, we construct a real-algebraic function whose Reeb (Kronrod-Reeb) graph is a graph respecting some algebraic domain: a graph for this is called Poincar\'e-Reeb graph. The Reeb graph of a smooth function is defined as a natural…

General Topology · Mathematics 2023-02-21 Naoki Kitazawa

The class of special generic maps is a natural class of smooth maps containing Morse functions on spheres with exactly two singular points and canonical projections of unit spheres. We find new restrictions on such maps on $6$-dimensional…

Algebraic Topology · Mathematics 2022-06-03 Naoki Kitazawa

Stable fold maps are fundamental tools in studying a generalized theory of the theory of Morse functions on smooth manifolds and its application to geometry of the manifolds. It is important to construct explicit fold maps systematically to…

Algebraic Topology · Mathematics 2015-03-20 Naoki Kitazawa

On a smooth manifold, we associate to any closed differential form a mapping cone complex. The cohomology of this mapping cone complex can vary with the de Rham cohomology class of the closed form. We present a novel Morse theoretical…

Differential Geometry · Mathematics 2024-06-21 David Clausen , Xiang Tang , Li-Sheng Tseng

Nash and Tognoli show that smooth closed manifolds can be the zero sets of some real polynomial maps and non-singular. The canonical projections of spheres naturally embedded in the $1$-dimensional higher Euclidean spaces and some natural…

Algebraic Geometry · Mathematics 2024-04-09 Naoki Kitazawa