MolFoundry · growing planar trees

One query discovers four counts

Count a left spine of at least three internal vertices. Composition discovers the additional observables needed for an exact expectation ODE.

1 · Rules & state space

Insertion with the old subtree on the left
At a selected edge, insert a binary vertex and a leaf. The old subtree goes left or right; each choice has rate κ. This is a tree schematic; the DPO encoding uses additional vertices and edge types. View DPO rule in MolFoundry.
Minimal tree with a left spine of three internal vertices
A minimal tree with P3=1. P3 sums the I, L and R typed-stem pattern counts.

Tree growth and multiplicities

All planar trees through three insertions. A label ×m means m distinct rule matches reach the same tree; the transition rate is mκ. Select a tree to open its incidence graph in MolFoundry.

Inspect individual trees

2 · Inputs & semantics

Six rules and their graph language

Finite rooted planar full binary trees, with an exterior stem. I/L/R edge types encode the root, left and right child incidences. The six DPO rules implement the insertions of the SqPO source model on this language; deleted edge-nodes have exactly their matched incidences.

The pictures show tree insertions; the links open the DPO rules in MolFoundry.

3 · Observable discovery

Discovered patterns and composition steps

The drawings are minimal tree witnesses; each coordinate sums three typed-stem identities. The Pk labels describe the discovered graph shapes.

Minimal tree witness for P3
P3 · full ordered-binary left-spine pattern of depth 3
P3_I · P3_L · P3_R
Minimal tree witness for P2
P2 · full ordered-binary left-spine pattern of depth 2
P2_I · P2_L · P2_R
Minimal tree witness for P1
P1 · full ordered-binary left-spine pattern of depth 1
P1_I · P1_L · P1_R
Minimal tree witness for E
E · all selectable directed typed edges
E_I · E_L · E_R

4 · ODE & pJC

Seed P3 → discovered P2, P1, E. The four-dimensional expectation system closes. Full event partition ↓

DerivativeComputed right-hand sideNew coordinate
d E[P3]/dtκ E[-4 P3 + 4 P2]P2
d E[P2]/dtκ E[-2 P2 + 3 P1]P1
d E[P1]/dtκ E[2 E]E
d E[E]/dtκ E[4 E]—
Full event partition

The full event partition additionally uses the counting identity N(r,s)=P_(r+s). The expectation ODE follows from composition and tree-count reduction.

ClassΔ(E,P1,P2,P3)Rate / κ
J0[2, 1, 0, 0]2*E - 3*P1 + 2*P2 - P3
J1[2, 1, 1, 0]3*P1 - 6*P2 + 3*P3
J2[2, 1, 1, 1]4*P2 - 3*P3
J3[2, 1, 0, -1]P3

5 · Initial states

Start from one leaf and its exterior stem: E=1 and P1=P2=P3=0. All six rules share κ, called rho in the input.

6 · Dynamics

Numerical integration of the generated linear coefficients; no finite-state truncation.

Condition on the number of insertions

Here n is the number of insertion events, not elapsed time. These distributions propagate the generated event weights with exact integers.