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math.GT2025
A cut-and-paste mechanism to introduce fundamental group and construct new four-manifolds
Valentina Bais, Rafael Torres
We introduce a simple cut-and-paste mechanism to construct both orientable and nonorientable four-manifolds from a given initial one. This mechanism alters the fundamental group wh…
math.DG2025
An observation on the existence of stable generalized complex structures on ruled surfaces
Rafael Torres
We point out that any stable generalized complex structure on a sphere bundle over a closed surface of genus at least two must be of constant type.