A neat and tidy example of generating a structure from atoms and signatures occurred to me : adenine. It is known that this molecule forms readily from HCN under conditions similar to those thought to exist on the early Earth.

Each signature (

Anyway, the point is that the structure is almost exactly 6 C-N units (ignoring hydrogens and multiple bonds). A C-N is very similar to a height-1 signature, and the height-1 signatures for adenine are shown in the figure below:

Each signature (

**a**-**e**) is mapped to an atom in the original structure, and then a table is shown of the maximum number of compatible bonds possible between each pair of signatures. Note that the table is not symmetric, as the compatibility operation is not commutative. Also, notice that the diagonal is not all 0 - bonds can form between atoms that both have**b**as a target signature.Although these target signatures are smaller than the diameter of the adenine molecular graph, they still seem to define it completely. However, they are not guaranteed to produce only adenine as a solution - there may be other molecules with the same signature of (3

**a**+ 2**b**+3**c**+**d**+**e**).Edit: Hmmm. That's not actually adenine, is it? In fact, it doesn't seem to be in ChEBI either. I probably should check my examples before posting them to the world.

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