**Symmetry**

The square lattice's symmetry category is wallpaper group p4m. A pattern with this lattice of translational symmetry cannot have more, but may have less symmetry than the lattice itself. An upright square lattice can be viewed as a diagonal square lattice with a mesh size that is √2 times as large, with the centers of the squares added. Correspondingly, after adding the centers of the squares of an upright square lattice we have a diagonal square lattice with a mesh size that is √2 times as small as that of the original lattice. A pattern with 4-fold rotational symmetry has a square lattice of 4-fold rotocenters that is a factor √2 finer and diagonally oriented relative to the lattice of translational symmetry.

With respect to reflection axes there are three possibilities:

- None. This is wallpaper group p4.
- In four directions. This is wallpaper group p4m.
- In two perpendicular directions. This is wallpaper group p4g. The points of intersection of the reflexion axes form a square grid which is as fine as, and oriented the same as, the square lattice of 4-fold rotocenters, with these rotocenters at the centers of the squares formed by the reflection axes.

p4, +, (442) | p4g, (4*2) | p4m, (*442) |
---|---|---|

Wallpaper group p4, with the arrangement within a primitive cell of the 2- and 4-fold rotocenters (also applicable for p4g and p4m). A fundamental domain is indicated in yellow. | Wallpaper group p4g. There are reflection axes in two directions, not through the 4-fold rotocenters. |
Wallpaper group p4m. There are reflection axes in four directions, through the 4-fold rotocenters. In two directions the reflection axes are oriented the same as, and as dense as, those for p4g, but shifted. In the other two directions they are linearly a factor √2 denser. |

Read more about this topic: Square Lattice

### Other articles related to "symmetry":

**Symmetry**

...

**Symmetry**suggests that the probability is independent of the color chosen, so that the information about which color is shown does not affect the odds that both sides have the same ...

... (iii) The parts included in any one plane must have trigonal

**symmetry**, without or with reflection ... This secures icosahedral

**symmetry**for the whole solid ... cases where the parts can be divided into two sets, each giving a solid with as much

**symmetry**as the whole figure ...

**Symmetry**

... it is invariant under the action of a group

**symmetry**, such as translational invariance ... Thus a

**symmetry**in the Hamiltonian becomes a

**symmetry**of the correlation function (and vice-versa) ... This

**symmetry**has a critically important interpretation in probability theory it implies that the Gibbs measure has the Markov property that is, it is ...

**Symmetry**Set

... In geometry, the

**symmetry**set is a method for representing the local symmetries of a curve, and can be used as a method for representing the shape of objects by finding the topological skeleton ... The medial axis, a subset of the

**symmetry**set is a set of curves which roughly run along the middle of an object ...

**Symmetry**in Aesthetics

... The relationship of

**symmetry**to aesthetics is complex ... symmetries, and in particular bilateral

**symmetry**, seem to be deeply ingrained in the inherent perception by humans of the likely health or fitness of other living creatures, as can be ... in turn drives a powerful tendency to create artifacts with similar

**symmetry**...

### Famous quotes containing the word symmetry:

“What makes a regiment of soldiers a more noble object of view than the same mass of mob? Their arms, their dresses, their banners, and the art and artificial *symmetry* of their position and movements.”

—George Gordon Noel Byron (1788–1824)