Formal Modelling of PBFT Consensus Algorithm in Event-B

Listing 9

Context ‘Ma1_ctx’.

Context Ma1_ctx extends Ma0_ctx

Sets value

Constants contents Correct_value Faulty_value H

Axioms

 @axm1 value≠∅

 @axm2 finite(value)

 @axm3 partition(Value,Correct_value,Faulty_value)

 @axm4 card(Correct_value)=card(Faulty_value)

 @axm5 contents∈message↣(ℕ×value)

 @axm6 ∀x,y·x∈message∧y∈message∧x≠y⇒

prj2(contents(x))≠prj2(contents(y))

 @axm7 ∀x·x∈message⇒(∃y·y∈message∧x≠y∧

    (prj1(contents(x))=prj1(contents(y))+1∨

     prj1(contents(x))=prj1(contents(y))−1))

 @axm8 ∀x,y·x∈message∧y∈message∧x≠y∧⇒

(prj2(contents(x))∈Correct_value∧prj2(contents(y))∈Faulty_value)∨

(prj2(contents(x))∈Faulty_value∧prj2(contents(y))∈Correct_value)

 @axm9 H=2

End