Encoding and accessible leaves

Define the rooted encoders recursively:

There are $5^h$ physical leaves and one root logical qubit. At every node choose child positions $1,2,3$ as accessible and discard positions $4,5$ into the inaccessible complement. The accessible set $A_h$ has

leaves.

For $h=2$, the network has one root tensor and five child tensors, with twenty-five physical leaves. The accessible nine are

This is the small multi-tensor benchmark.

Streaming deliveries use depth-first order: all accessible leaves of child 1, then child 2, then child 3, recursively.