bijeccions

[Ai][Aj][ Si ( i != j ) ==> ( a_{i} != a_{j} ) ]

[Ai][Aj][ Si ( i != j ) ==> ( b_{i} != b_{j} ) ]

< f: {a_{1},...(n)...,a_{n}} ---> {b_{1},...(n)...,b_{n}} & a_{k} --> f(a_{k}) = b_{k} >

f(a_{i}) = f(a_{j})

b_{i} = b_{j}

i = j

< f: A\{a_{1},...(n)...,a_{n}} ---> A\{b_{1},...(n)...,b_{n}} & ...

... a_{k} --> f(a_{k}) = b_{k} & x € A --> f(x) = x >

[1]:

f(a_{i}) = f(a_{j})

b_{i} = b_{j}

i = j

[2]:

x != y

f(x) != f(y)