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Definition df-suc 2944
Description: Define the successor of a class. When applied to an ordinal number, the successor means the same thing as "plus 1" (see oa1suc 4148). 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 3034), so that the successor of any ordinal class is still an ordinal class (ordsuc 3055), 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 2940 . 2 class suc A
31csn 2399 . . 3 class {A}
41, 3cun 2035 . 2 class (A u. {A})
52, 4wceq 953 1 wff suc A = (A u. {A})
Colors of variables: wff set class
This definition is referenced by:  suceq 3024  elsuci 3025  elsucg 3026  elsuc2g 3027  suc0 3033  sucprc 3034  unisuc 3036  sssucid 3037  sucexb 3038  sucid 3041  suceloni 3052  orddif 3065  onuninsuc 3098  tfrlem10 3905  df2o2 4125  oarec 4180  limensuci 4486  phplem1 4488  pssnn 4513  unifi 4532  fiint 4534  fodomfi 4540  pwfi 4545  pm54.43 4546  sucprcreg 4572  infensuc 4610  ranksuc 4672  sucxpdom 4818  cfsuc 4887  cda1en 4898
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