Metamath Proof Explorer


Theorem pstr

Description: A poset is transitive. (Contributed by NM, 12-May-2008) (Revised by Mario Carneiro, 30-Apr-2015)

Ref Expression
Assertion pstr ⊢ R ∈ PosetRel ∧ A R B ∧ B R C → A R C

Proof

Step Hyp Ref Expression
1 pslem ⊢ R ∈ PosetRel → A R B ∧ B R C → A R C ∧ A ∈ ⋃ ⋃ R → A R A ∧ A R B ∧ B R A → A = B
2 1 simp1d ⊢ R ∈ PosetRel → A R B ∧ B R C → A R C
3 2 3impib ⊢ R ∈ PosetRel ∧ A R B ∧ B R C → A R C