are two different coordination sequences arising in this way. The degree-four sequence is the same as for the square grid. Special cases Catalan tiling The snub square tiling, made of two squares and three equilateral triangles around each vertex, has a bilaterally symmetric Cairo tiling as its dual tiling. The Cairo tiling can be formed from the snub square tiling by placing a vertex of the Cairo tiling at the center of each square or triangle of the snub square tiling, and connecting these vertices by edges when they come from adjacent tiles. Its pentagons can be circumscribed around a circle. They have four long edges and one short one with lengths in the ratio . The angles of these pentagons form the sequence 120°, 120°, 90°, 120°, 90°. The snub square tiling is an Archimedean tiling, and as the dual to an Archimedean tiling this form of the Cairo pentagonal tiling is a Catalan tiling or Laves tiling. It is one of two monohedral pentagonal tilings that, when the tiles have unit area, minimizes the perimeter of the tiles. The other is also a tiling by circumscribed pentagons with two right angles and three 120° angles, but with the two right angles adjacent; there are also infinitely many tilings formed by combining both kinds of pentagon. Tilings with collinear edges Pentagons with integer vertex coordinates , , and , with four equal sides shorter than the remaining side, form a Cairo tiling whose two hexagonal tilings can be formed by flattening two perpendicular tilings by regular hexagons in perpendicular directions, by a ratio of . This form of the Cairo tiling inherits the property of the tilings by regular hexagons (unchanged by the flattening), that every edge is collinear with infinitely many other edges. Tilings with equal side lengths The regular pentagon cannot form Cairo tilings, as it does not tile the plane without gaps. There is a unique equilateral pentagon that can form a type 4 Cairo tiling; it has five equal sides but its angles are unequal, and its tiling is bilaterally symmetric. Infinitely many other equilateral pentagons can form type 2 Cairo tilings. Applications Several streets in Cairo have been paved with the collinear form of the Cairo tiling; this application is the origin of the name of the tiling. As of 2019 this pattern can still be seen as a surface decoration for square tiles