Quég​uiner-Mathieu–Semenov–Zainoulline conjecture on the J-invariant after generic splitting

Let (A,σ)(A,\sigma) be a central simple algebra with orthogonal involution and trivial discriminant, and let G=PGO+(A,σ)G=\operatorname{PGO}^+(A,\sigma) be the connected component of its automorphism group, an adjoint group of type DnD_n. Write

J(G)=(j1,,jr).J(G)=(j_1,\ldots,j_r).

Let FAF_A be the function field of the Severi–Brauer variety of AA, a generic splitting field of AA, and denote by (ji)FA(j_i)_{F_A} the ii-th component of the JJ-invariant after extension to FAF_A. Quég​uiner-Mathieu–Semenov–Zainoulline conjecture. The remaining components do not change after generic splitting of AA:

ji=(ji)FAfor i=2,,r.j_i=(j_i)_{F_A}\qquad\text{for }i=2,\ldots,r.

The first component is known to vanish after splitting AA; the conjecture asserts that all the other components are already unchanged by this generic splitting. The source gives no resolution, so the conjecture is recorded as open.

Sources & referencesView supporting material

Primary source

Maksim Zhykhovich, “The J-invariant over splitting fields of Tits algebras”, arXiv:2205.02819 (2023).

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