Databases and Systems

Binary relations
Figure 1 : Level of abstractions in molecular biology.
An important concept in KEGG is the binary relation that represents any relation
between two elements [3]. Of course, the real-world data can better be represented by
considering ternary, quaternary, and higher relations, but for the sake of logical
simplicity and computational efficiency KEGG imposes the view of binary relations.
A major class of binary relation is an interaction between two molecules or between
two genes, which may be considered wiring information of the biological system.
Generally speaking, building blocks can contain all necessary wiring information as
in the jigsaw puzzle, but in reality building blocks of life are more like Lego blocks
that can be used in many different ways. KEGG computerizes the information of
interactions and wiring, thus complementing the existing databases for the
information of building blocks.
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