# brain of mat kelcey

## e10.2 tgraph crawl order example

September 21, 2009 | View Comments

let's consider an example of the crawl order for tgraph...

we seed our frontier with 'a' and bootstrap cost of 0.

fetching the info for 'a' shows 2 outedges to 'b' and 'c', from our cost formula these all have cost 0 + 1 + Log10(2+1) = 1.6

our frontier becomes [ {b,1.6}, {c,1.6} ]

next is 'b' and see it has an outdegree of 3, these nodes, b1 -> b3, all have a cost of 1.6 + 1 + Log10(3+1) = 3.2

our frontier becomes [ {c,1.6}, {b1,3.2}, {b2,3.2}, {b3,3.2} ]

next is 'c' with an outdegree of 15. these 15 nodes, c1 -> c15, have cost 1.6 + 1 + Log10(16) = 3.8

our frontier is now [ {b1,3.2}, {b2,3.2}, {b3,3.2}, {c1,3.8} ... {c15,3.8} ]

we would then continue with the 'b' nodes before the 'c' ones

note that this cost system is more than just an ordering, it allows an element at depth n+1 to be checked an element at depth n, if the cost of the latter is high enough.