Definition df-ord 6351

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 6347	. 2 wff Ord 𝐴
3	1	wtr 5209	. . 3 wff Tr 𝐴
4		cep 5548	. . . 4 class E
5	1, 4	wwe 5601	. . 3 wff E We 𝐴
6	3, 5	wa 399	. 2 wff (Tr 𝐴 ∧ E We 𝐴)
7	2, 6	wb 208	1 wff (Ord 𝐴 ↔ (Tr 𝐴 ∧ E We 𝐴))

This definition is referenced by:  ordeq  6355  ordwe  6361  ordtr  6362  trssord  6365  ordelord  6370  ord0  6402  ordon  7762  dford5  7769  dfrecs3  8345  dford2  9577  smobeth  10546  gruina  10778  dford5reg  36135  dfon2  36145  oaun3lem1  43956