On Conic-Line Curves of Special Pencils

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2026-05-22
A pencil is a line in the projective space of homogeneous polynomials in C[x0,x1,x2] of some degree d > 2. The number m of curves whose irreducible components are only lines in some pencils of degree d curves plays an important role for the existence of special line arrangements, which are called (m,d)−nets. It is known that m cannot exceed 4. When the degree of each irreducible component of a curve is at most 2, this curve is called a conic-line curve and it is a union of lines or irreducible conics in the complex projective plane. Using purely algebraic–geometric and combinatorial arguments, we establish explicit upper bounds on m corresponding to the number of members of concurrent lines. In this talk, I will present my research on constraints on the number m of conic-line curves that can appear in special pencils. I establish an upper bound, showing that m ≤ 6. I conjecture that for large values of d, the number m of conic-line curves in a pencil must be at most 4.
IMBM* Istanbul Topology Days: A Conference on Developments in Contact Topology, Mapping Class Groups, and Beyond
Citation Formats
H. Suluyer, “On Conic-Line Curves of Special Pencils,” presented at the IMBM* Istanbul Topology Days: A Conference on Developments in Contact Topology, Mapping Class Groups, and Beyond, İstanbul, Türkiye, 2026, Accessed: 00, 2026. [Online]. Available: https://hdl.handle.net/11511/119952.