Non-holomorphic Kaehler submanifolds of Euclidean space

This article is about non-holomorphic isometric immersions of Kaehler manifolds into Euclidean space f : M 2 n → R 2 n + p f M²ⁿ→ R²ⁿ⁺ᵖ , p ≤ n − 1 p≤ n-1 , with low codimension p ≤ 11 p≤ 11 . In particular, it addresses a conjecture proposed by J. Yan and F. Zheng. The claim that if the index of complex relative nullity of the submanifold satisfies ν f c > 2 n − 2 p ν _f^c>2n-2p at any point, then f ( M ) f(M) can be realized as a holomorphic submanifold of a non-holomorphic Kaehler submanifold of R 2 n + p R²ⁿ⁺ᵖ of larger dimension. This conjecture had previously been confirmed by Dajczer-Gromoll for codimension p = 3 p=3 , and then by Yan-Zheng for p = 4 p=4 . For codimension p ≤ 11 p≤ 11 , we already showed that the pointwise structure of the second fundamental form of the submanifold aligns with the anticipated characteristics, assuming the validity of the conjecture. In this paper, we confirm the conjecture until codimension p = 6 p=6 , whereas for codimensions 7 ≤ p ≤ 9 7≤ p≤ 9 it is also possible that the submanifold exhibits a complex ruled structure with rulings of a specific dimension. Moreover, we prove that the claim of the conjecture holds for codimensions 7 ≤ p ≤ 11 7≤ p≤ 11 albeit subject to an additional assumption.