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Keyword reference for symmetry

Question 34 (2007):

Submission reference: IN1358

In the replicators slide 66, the greater process is said that it doesen't have symmetric output. What is symmetric output? Why does greater process not have symmetric output?

Answer 34:

The greater process takes one number from each of its input channels and sends the smaller of them down its first output channel and the greater of them down its second output channel. Therefore, when wiring it up in a network, the order in which we plug in the output channels matters – there is no symmetry. On the other hand, the order in which we plug inthe input channels does not matter – there is symmetry. Thus:

  greater (a, b, c, d)

has the same effect as:

  greater (b, a, c, d)

but is different from:

  greater (a, b, d, c)

which sends the larger numbers down channel c (wheras the first two instances both send the larger down d).

Note: the first two arguments of greater are its input channels – the second two arguments are its otuput channels.

Keywords: greater , symmetry