In BAsCET, the activation value is propagated from a semantic node to another.
Let's start from the example shown in the link explanation.
/----------------\ /--------------\
| S: birthday | | S: cake |
+----------------+ +--------------+
| CI: 80 | /-----------------\ | CI: 70 |
| AV: 100 % +-----+ T: eat | W: 95% +-----+ AV: 0% |
| DR: 2 | \-----------------/ | DR: 5 |
| Ag: ComputeDay | | Ag: CookCake |
\----------------/ \--------------/
Propagating the activation value of birthday through the link eat to the node cake will give the following Concept Network:
/----------------\ /--------------\
| S: birthday | | S: cake |
+----------------+ +--------------+
| CI: 80 | /-----------------\ | CI: 70 |
| AV: 98 % +-----+ T: eat | W: 95% +-----+ AV: 86% |
| DR: 2 | \-----------------/ | DR: 5 |
| Ag: ComputeDay | | Ag: CookCake |
\----------------/ \--------------/
The activation value AVt+1i of a node i at the instant t + 1, after propagation, is expressed as the sum of its old activation value AVti and the other nodes' influence Ii, minus a deactivation Di, depending on its decay rate DRi.
AVt+1i = AVti + Ii - Di
The influence of other nodes could be given by this classical formula:
Ii = (Σj≠i Aj x Wij) / 100
but it lets an unbalanced influence between nodes with many neighbours (influencing them) and nodes with almost none.
That's the reason why BAsCET use a little more complicated influence, with a logarithmic behaviour.
As the birthday node has no incoming link, Ibirthday is null.
Dbirthday = 100 x 2 / 100 = 2
So, its new activation value AV1 = AV0 + I - D = 100 + 0 - 2 = 98.
As far as the cake node is concerned, it is different: its activation value is null, and so is its deactivation. However, it is influenced by birthday:
Icake = (A0birthday x Wbirthday,cake) / ( 100 x Divcake ) = 100 x 95 / ( 100 x Divcake ) = 95 / Divcake
Divcake = ln 4 / ln 3 ~ 1.0986, so Icake ~ 86.
At last, A1birthday = 0 + 86 - 0 = 86
In this example, one could add a candle node, that would be associated to the cake and birthday symbols. One could add a link from cake to candle labeled by birthday; so, when birthday and cake are both activated, this link activate candle.