Pattern

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Like a chess board, the world is divided in squares, the state of each field depending on the state of its neighbour fields. In our case, the number of neighbours is eight: the fields below, above, left and right, as well as up-left, up-right, down-left and down-right. The edges of the chess board are linked, which means that everything leaving the screen to the right will turn up again on the left side, and what leaves to the top will enter again from the bottom. This is just for simplification, the absence of an edge creating equivalent conditions for each field. The resulting form of the chess bord is a torus, comparable to a tire. Time runs in steps ("moves" or "days"). Below the board, the population is presented in the corresponding colour. The height of the frame represents the total number of the fields on the board.

WATOR

Published by A. K. Dewdney in 1984, Wator (WAter TORus) is the classic among this kind of computer simulations.

In the sea, sharks (grey) and fishes (blue) swim around. The direction of their movements is determined by random. If a shark enters a field occupied by a fish, it will eat it up.

You can enter the initial populations of sharks and fish, and decide about the number of days for their reproduction, as well as the number of days for a shark to survive without food before starving to death.

If you click the box "Sharks smell fish", the dynamics of the game will change : The sharks will no longer move randomly, but prefer the neighbouring cases occupied by a fish.

EPIDEMIC

This applet simulates the dynamics of a (non lethal) epidemic influenza.

The healthy (black) humans move randomly. If you press the button "Infection", one individual will fall ill (red).

If a healthy person arrives at one of the eight neighbouring fields to an infected one, this one will also fall ill (turn red). After some time, it will be well again and immune (blue) for some days; during this time, it can't get contaminated. After the end of the immunity period, it will turn black again.

You can determine the population, the duration of the disease and the duration of the immunity period. Furthermore, you can erect geographical obstacles by dragging the mouse. Will this help to stop the disease?

CRO MAGNON

Has Man exterminated the mammoth?

And together with it some other big mammals, such as the woolly rhinoceros, the cave bear, the large-horned deer, the Neanderthal Man, the aurochs, the primeval horse,...? In this game, it depends. On what? You can select it yourself:

First, there is the grass of the ice-age prairie. Depending on the climate, it can grow faster or slower.

Via the corresponding button, you can put "new mammoths" into the game. Where they feast, no grass will grow for some time. You can determine, how fast they increase and how long they survive without food.

Now you can release, via the appropriate button, some Cro Magnon hunters on the mammoths. Their success also depends on their propagation time and their endurance towards hunger. (like in the Wator version "Sharks smell fish", the hunters prefer the neighbouring fields where they find food).

What did humans live from after the mammoth had vanished? They did not starve, like the sharks in Wator, but they invented agriculture. With the help of the button "new fields", you can plant acres in the prairie. For the hunters, they are as good a source of food as a mammoth, except that these don't disappear after consumption. For a mammoth, however, a corn field is the same as a grass area.

So, has Man exterminated the mammoth or has he not?

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