Turing's "On Ordinal Logic Systems" solved the π ₂ structure problem ((∀ x) (∃ y) R (x, y)) using the techniques of oracle Turing machines and superpoor iterations (where second-order predicates represent semantics). Bitcoin is a concrete example of this method, and for any TX, there exists a recursive block to confirm that TX is not duplicated. Among them, Bitcoin's blocks are in a super poor iterative recursive mode, and the model for each block to determine whether it is the longest chain is a relative judgment mode of the oracle Turing machine. And the syntax between each block is irrelevant, and the blocks are represented by the decision hash index of the oracle machine, corresponding to the axiomatic hierarchical representation of Turing super poor iteration. The links between blocks are determined by oracle machines, and the growth of trust is axiomatic and consolidated through super poor iterations. This oracle machine+super poor iteration process generates a simple syntactic structure that goes beyond first-order predicate systems, achieving the expression of trust/responsibility in mechanical automatic semantic expression.