Definition df-ord 6321

Description: Define the ordinal predicate, which is true for a class that is transitive and is well-ordered by the membership relation. Variant of definition of [BellMachover] p. 468.

Some sources will define a notation for ordinal order corresponding to < and ≤ but we just use ∈ and ⊆ respectively.

(Contributed by NM, 17-Sep-1993.)

Assertion

Ref	Expression
df-ord	⊢ (Ord 𝐴 ↔ (Tr 𝐴 ∧ E We 𝐴))

Detailed syntax breakdown of Definition df-ord

Step	Hyp	Ref	Expression
1		cA	. . 3 class 𝐴
2	1	word 6317	. 2 wff Ord 𝐴
3	1	wtr 5206	. . 3 wff Tr 𝐴
4		cep 5524	. . . 4 class E
5	1, 4	wwe 5577	. . 3 wff E We 𝐴
6	3, 5	wa 395	. 2 wff (Tr 𝐴 ∧ E We 𝐴)
7	2, 6	wb 206	1 wff (Ord 𝐴 ↔ (Tr 𝐴 ∧ E We 𝐴))

This definition is referenced by:  ordeq  6325  ordwe  6331  ordtr  6332  trssord  6335  ordelord  6340  ord0  6372  ordon  7724  dford5  7731  dfrecs3  8306  dford2  9533  smobeth  10501  gruina  10733  dford5reg  35976  dfon2  35986  oaun3lem1  43683