Changes

Nodes in a graph depict ''records'' in computer memory.  A record is a collection of data that can be thought to reside at a specific ''address''.  For semioticians, an address can be recognized as a type of index, and is commonly spoken of, on analogy with demonstrative pronouns, as a ''pointer'', even among computer programmers who are otherwise innocent of semiotics.

Nodes in a graph depict ''records'' in computer memory.  A record is a collection of data that can be thought to reside at a specific ''address''.  For semioticians, an address can be recognized as a type of index, and is commonly spoken of, on analogy with demonstrative pronouns, as a ''pointer'', even among computer programmers who are otherwise innocent of semiotics.

At the next level of concretion, a record/node can be represented as follows:

At the next level of concreteness, a pointer-record structure may be represented as follows:

| [[Image:Logical_Graph_Figure_11_Visible_Frame.jpg|500px]]

|}

` ` ` ` ` | datum_1 datum_2 datum_3 ... | ` ` ` ` ` ` ` ` ` `

` ` ` ` ` | index_0 ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` `

This depicts the circumstance that ''index''₀ is the address of the record in question, which record contains the data: ''datum''₁, ''datum''₂, ''datum''₃, …, and so on.

This portrays the pointer <math>\operatorname{index}_0</math> as the address of a record that contains the following data:

What makes it possible to represent graph-theoretical structures as data structures in computer memory is the fact that an address is just another datum, and so we can have a circumstance like this:

| <math>\operatorname{datum}_1, \operatorname{datum}_2, \operatorname{datum}_3, \ldots,</math> and so on.

What makes it possible to represent graph-theoretical structures as data structures in computer memory is the fact that an address is just another datum, and so we may have a state of affairs like the following:

 

{| align="center" cellpadding="10"

| [[Image:Logical_Graph_Figure_12_Visible_Frame.jpg|500px]]

` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` o-----o o-----o ` ` ` ` ` ` `

|}

` ` ` ` ` o---------------------|-------|-----------o ` ` ` `

` ` ` ` ` | datum_1 datum_2 ... index_1 index_2 ... | ` ` ` `

` ` ` ` ` | index_0 ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` `

Back at the abstract level, it takes three nodes to represent the three data records, with a root node connected to two other nodes.  The ordinary bits of data are then treated as labels on the nodes:

Back at the abstract level, it takes three nodes to represent the three data records, with a root node connected to two other nodes.  The ordinary bits of data are then treated as labels on the nodes:

| [[Image:Logical_Graph_Figure_13_Visible_Frame.jpg|500px]]

|}

` ` ` ` ` | `/` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` `

` ` ` ` ` | / ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` `

` ` ` ` ` |/` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` `

Notice that, with rooted trees like these, drawing the arrows is optional, since singling out a unique node as the root induces a unique orientation on all the edges of the tree, ''up'' being the same as ''away from the root''.

Notice that, with rooted trees like these, drawing the arrows is optional, since singling out a unique node as the root induces a unique orientation on all the edges of the tree, ''up'' being the same as ''away from the root''.