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Definition df-suc 2949
Description: Define the successor of a class. When applied to an ordinal number, the successor means the same thing as "plus 1" (see oa1suc 4154). 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 3039), so that the successor of any ordinal class is still an ordinal class (ordsuc 3060), 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 2945 . 2 class suc A
31csn 2405 . . 3 class {A}
41, 3cun 2041 . 2 class (A u. {A})
52, 4wceq 954 1 wff suc A = (A u. {A})
Colors of variables: wff set class
This definition is referenced by:  suceq 3029  elsuci 3030  elsucg 3031  elsuc2g 3032  suc0 3038  sucprc 3039  unisuc 3041  sssucid 3042  sucexb 3043  sucid 3046  suceloni 3057  orddif 3070  onuninsuc 3103  tfrlem10 3911  df2o2 4131  oarec 4186  limensuci 4492  phplem1 4494  pssnn 4519  unifi 4538  fiint 4540  fodomfi 4546  pwfi 4551  pm54.43 4552  sucprcreg 4580  infensuc 4618  ranksuc 4680  sucxpdom 4826  cfsuc 4895  cda1en 4906
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