1 – Aut | Notations

• $S=\mathrm{N}\mathrm{S}(X)$ denotes the Néron-Severi lattice of the $K3$ surface $X$.
• $\mathbb{L}$ denotes an even hyperbolic lattice.
• ${\mathcal{P}}_{\mathbb{L}}$ denotes the positive cone of $\mathbb{L}$.
• ${\mathcal{P}}_S$ denotes the positive cone of $S$.
• Denote by $\bar{C}$ the topological closure of a set $C$.

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