One unit, repeated forever. No gaps. No overlaps. The plane fills itself. What Escher called the regular division of the plane: a single shape - the fundamental domain - congruent in every copy, locking edge to edge with no room left and no piece spared. The same curve becomes the head of one tile and the tail of the next. Colors mark rhythm, not difference. This is wallpaper group p1 - the simplest of the seventeen ways a plane can tile. The work is a proof: any curve drawn corner to corner, mirrored on the opposite edge, tessellates the plane. Without exception. Title FUNDAMENTAL DOMAIN Year 2026 Series VELVET - Tessellation Studies Symmetry group p1 (pure translation, wallpaper group) Edition 1/1 Format JPEG Color space sRGB Resolution 5760 × 3240 px Aspect ratio 16:9 Density 300 DPI Print size 19.2" × 10.8" (48.8 × 27.4 cm) Color depth 8-bit per channel · 24-bit RGB · 16.7M colors Quality JPEG 95 File size 3.2 MB Algorithm Sum-of-Gaussians boundary curve (5 bumps on right edge, 4 on top edge); endpoint pinning f(0)=f(1)=0; deterministic per-tile coloring by positional hash; ~22% of tiles carry 45° interior hatching. Tile size 540 × 540 px (output resolution) Tile count ~70 visible tiles Rendering 2× supersampling, LANCZOS downsample, 160 boundary samples per edge. Engine Python 3.11 + Pillow Origin Generative · deterministic · fully reproducible from script + parameters