I understand that: an economic protocol defines a fitness (a.k.a score) function that maps a block (a context?) to a sequence of bytes (the fitness of the block). The fitness is used by the shell to arbitrate between candidate blocks at the same level of the chain.
Suppose we have the following chain, where fitness is a sequence of two bytes, lexicographically ordered.
Genesis - fitness 0 0 - level 0 A - fitness 1 0 - level 1 B - fitness 2 0 - level 2
Are the following block injections accepted or rejected by the shell:
- a block B' on top of A, with fitness 2 0
- a block A' on top of Genesis, with fitness 1 1