Geometric Clarification of the GEP Lattice Structure: Triangular vs. Hexagonal Lattice and Stability of K_crit = 3/2

In previous GEP publications, the fundamental 2D projection of the tetrahedral network was incorrectly referred to as a "hexagonal lattice." The correct designation is a triangular lattice (coordination number z=6). Since all simulations were implemented on the triangular lattice from the outset, the numerical results remain unchanged. The clarification is nevertheless physically important: the triangular and hexagonal (honeycomb) lattices are not dynamically equivalent systems. We additionally present an analytical derivation of K_crit = 3/2 from linear stability analysis on the triangular lattice, providing a geometric explanation of the numerically observed critical value.