Collisions Between A and EBar Gliders

Although collisions with A gliders are not central to the demonstrtation that Rule 110 is universal, their presence is felt in certain critical places,

The most important is the flow of A tetramers coming in from the West, whose purpose is to stop the solitonic EBar gliders which have traversed all the C2 groupings in the static part of the Cyclic Tag System. But the tetramers do allow some spurious EBars to ride off into the sunset as a sort of counterflow to the tetramers. That the two possibilities exist and that their operations are so nicely synchronized is both a marvel and a source of instability.

Table 1: A's can almost pass EBar's, except that in the two extreme alignments they turn them into E2's and stop. An A tetrad ([four equally spaced A's] vs. tetramer [block of four A's]) uniformly yields C2's.

align	monomer	dimer	trimer	triplet	tetramer	tetrad	pentad
hhi	E2	EBar, 2 B, Atet	D1	C3	EBar, Atet	C2	C1
hi	EBar, A	EBar, 2 A	C3	EBar, 3A	C2	C2	C1
mid	EBar, A	D2	D1	D1	C2	C2	C1
lo	EBar, A	E1	F, BBar, 2 B	EBar, 3A	F, BBar, B	C2	C1
llo	EBar, A	E1	F, BBar, 2 B	EBar, 3A	F, BBar, 2 B	C2	C1
top	E2	E1	D1	C3	C2	C2	C1

Table 1 summarizes some of the An-EBar collisions. Of course, collisions with A gliders can become quite complicated, given the variability of spacing between them. If they are well enough separated, the groups collide individually and the result is cummulative. Otherwise different combinations are likely to give a variety of results.

In the simplest combination, several T1's stick together; these are called polymers, with prefixes such as monomer, dimer, trimer, ..., designating the number of T1's.

Nearly as simple are arrangements which separates monomers by single ether tiles; they are called polyads, following the sequence monad, dyad, ... .

Table 1 contains an additional column labelled ``triplet,'' which is not a generic term but refers instead to one specific combination which forms part of the Cyclic Tag System. For this glider, the spacing between monomers is 2, 5.

On the next three pages, all the six possible collisions at different aspects are shown for the three most important classes of A-EBar collisions participating in the Cyclic Tag System. Of these, not all are realized, but it is useful to know what fraction of collisions was useful, and their exact configuration.

Figure 1: The six (A trimer, EBar) collisions. Three produce D1's, one produces a C3, the other two make leave 2 B's, a BBar, and an F.

Figure 2: The six A triplet - EBar collisions. Three are solitonic (but not strictly), two yield C3's, and the other one leaves a D1. Some collisions are seperable, others are interdependent.

Figure 3: The six (A tetramer, EBar) collisions. One is solitonic, three yield C2's, and the other two eventually result in the combination of an B, BBar5 and F.