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Definition df-ec 6139
Description: Define the 𝑅-coset of 𝐴. Exercise 35 of [Enderton] p. 61. This is called the equivalence class of 𝐴 modulo 𝑅 when 𝑅 is an equivalence relation (i.e. when Er 𝑅; see dfer2 6138). In this case, 𝐴 is a representative (member) of the equivalence class [𝐴]𝑅, which contains all sets that are equivalent to 𝐴. Definition of [Enderton] p. 57 uses the notation [𝐴] (subscript) 𝑅, although we simply follow the brackets by 𝑅 since we don't have subscripted expressions. For an alternate definition, see dfec2 6140. (Contributed by NM, 23-Jul-1995.)
Assertion
Ref Expression
df-ec [𝐴]𝑅 = (𝑅 “ {𝐴})

Detailed syntax breakdown of Definition df-ec
StepHypRef Expression
1 cA . . 3 class 𝐴
2 cR . . 3 class 𝑅
31, 2cec 6135 . 2 class [𝐴]𝑅
41csn 3403 . . 3 class {𝐴}
52, 4cima 4376 . 2 class (𝑅 “ {𝐴})
63, 5wceq 1259 1 wff [𝐴]𝑅 = (𝑅 “ {𝐴})
Colors of variables: wff set class
This definition is referenced by:  dfec2  6140  ecexg  6141  ecexr  6142  eceq1  6172  eceq2  6174  elecg  6175  ecss  6178  ecidsn  6184  uniqs  6195  ecqs  6199  ecinxp  6212
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