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Definition df-suc 2981
Description: Define the successor of a class. When applied to an ordinal number, the successor means the same thing as "plus 1" (see oa1suc 4300). Definition 7.22 of [TakeutiZaring] p. 41, who use "+ 1" to denote this function. Our definition is a generalization to classes. Although it is not conventional to use it with proper classes, it has no affect on a proper class (sucprc 3048), so that the successor of any ordinal class is still an ordinal class (ordsuc 3171), simplifying certain proofs. Some authors denote the successor operation with a prime (apostrophe-like) symbol, such as Definition 6 of [Suppes] p. 134 and the definition of successor in [Mendelson] p. 246 (who uses the symbol "Suc" as a predicate to mean "is a successor ordinal"). The definition of successor of [Enderton] p. 68 denotes the operation with a plus-sign superscript.
Assertion
Ref Expression
df-suc |- suc A = (A u. {A})

Detailed syntax breakdown of Definition df-suc
StepHypRef Expression
1 cA . . 3 class A
21csuc 2977 . 2 class suc A
31csn 2467 . . 3 class {A}
41, 3cun 2097 . 2 class (A u. {A})
52, 4wceq 992 1 wff suc A = (A u. {A})
Colors of variables: wff set class
This definition is referenced by:  suceq 3038  elsuci 3039  elsucg 3040  elsuc2g 3041  suc0 3047  sucprc 3048  unisuc 3049  sssucid 3050  sucid 3051  orddif 3065  sucexb 3166  suceloni 3170  onuninsuci 3194  tfrlem10 4221  df2o2 4277  oarec 4332  ac6sfilem2 4589  ac6sfi 4591  limensuci 4653  phplem1 4655  pssnn 4681  unifi 4701  fiint 4703  fodomfi 4709  pwfi 4714  pm54.43 4715  sucprcreg 4743  infensuc 4784  ranksuc 4846  unsnen 4983  sucxpdom 4996  cfsuc 5065  cda1en 5078  finsschain 11425  fbssint 11626  fcluscomplem 11732
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