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Definition df-cda 7678
Description: Define cardinal number addition. Definition of cardinal sum in [Mendelson] p. 258. See cdaval 7680 for its value and a description. (Contributed by NM, 24-Sep-2004.)
Assertion
Ref Expression
df-cda  |-  +c  =  ( x  e.  _V ,  y  e.  _V  |->  ( ( x  X.  { (/) } )  u.  ( y  X.  { 1o } ) ) )
Distinct variable group:    x, y

Detailed syntax breakdown of Definition df-cda
StepHypRef Expression
1 ccda 7677 . 2  class  +c
2 vx . . 3  set  x
3 vy . . 3  set  y
4 cvv 2727 . . 3  class  _V
52cv 1618 . . . . 5  class  x
6 c0 3362 . . . . . 6  class  (/)
76csn 3544 . . . . 5  class  { (/) }
85, 7cxp 4578 . . . 4  class  ( x  X.  { (/) } )
93cv 1618 . . . . 5  class  y
10 c1o 6358 . . . . . 6  class  1o
1110csn 3544 . . . . 5  class  { 1o }
129, 11cxp 4578 . . . 4  class  ( y  X.  { 1o }
)
138, 12cun 3076 . . 3  class  ( ( x  X.  { (/) } )  u.  ( y  X.  { 1o }
) )
142, 3, 4, 4, 13cmpt2 5712 . 2  class  ( x  e.  _V ,  y  e.  _V  |->  ( ( x  X.  { (/) } )  u.  ( y  X.  { 1o }
) ) )
151, 14wceq 1619 1  wff  +c  =  ( x  e.  _V ,  y  e.  _V  |->  ( ( x  X.  { (/) } )  u.  ( y  X.  { 1o } ) ) )
Colors of variables: wff set class
This definition is referenced by:  cdafn  7679  cdaval  7680
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