Rule 90

Rule 90 is an elementary cellular automaton based on the exclusive or function. It consists of a one-dimensional array of cells, each of which can hold either a 0 or a 1 value; in each time step all values are simultaneously replaced by the exclusive or of the two neighboring values.Martin, Odlyzko & Wolfram (1984) call it "the simplest non-trivial cellular automaton", and it is described extensively in Stephen Wolfram's 2002 book A New Kind of Science. When started from a random initial configuration, its configuration remains random at each time step; however, any configuration with only finitely many nonzero cells becomes a replicator that eventually fills all of the cells with copies of itself.

Rules

An elementary cellular automaton consists of a one-dimensional array of cells, each of which holds a single binary value, either 0 or 1. An assignment of values to all of the cells is called a configuration. The automaton is given an initial configuration, after which its configuration repeatedly changes in a sequence of discrete time steps. At each step, all cells are updated simultaneously, according to a pre-specified rule which determines the new value as a function of each cell's previous value and of the values in its two neighboring cells. All cells obey the same rule, which may be given either as a formula or as a rule table that specifies the new value for each possible combination of neighboring values.

Ruler

A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing, engineering and building to measure distances or to rule straight lines. The ruler is a straightedge which may also contain calibrated lines to measure distances.

Types

Rulers have long been made of different materials and in a wide range of sizes. Some are wooden. Plastics have also been used since they were invented; they can be molded with length markings instead of being scribed. Metal is used for more durable rulers for use in the workshop; sometimes a metal edge is embedded into a wooden desk ruler to preserve the edge when used for straight-line cutting. 12 inches or 30 cm in length is useful for a ruler to be kept on a desk to help in drawing. Shorter rulers are convenient for keeping in a pocket. Longer rulers, e.g., 18 inches (45 cm) are necessary in some cases. Rigid wooden or plastic yardsticks, 1 yard long and meter sticks, 1 meter long, are also used. Classically, long measuring rods were used for larger projects, now superseded by tape measure or laser rangefinders.

One percent

One percent (or 1%) may refer to:

Groups of people

Entertainment

Other uses

Rugby league gameplay

Like most forms of modern football, rugby league football is played outdoors on a rectangular grass field with goals at each end that are to be attacked and defended by two opposing teams. The rules of rugby league have changed significantly over the decades since rugby football split into the league and union codes. This article details the modern form of the game and how it is generally played today, however rules do vary slightly between specific competitions.

Basics

Field

A game of rugby league consists of two forty-minute halves, played by two teams on a rectangular grass field of 120 metres in length and 58–68 metres in width depending on the individual ground. In the middle of the field is the 50 metre "halfway" line. Each side of the field, on either side of the 50 metre line, is identical. 10 metres from the 50 metre line is the 40 metre line, followed by the 30, 20, 10 metre and goal or 'try' lines. This makes up 100 metres of field that is used for general play.