Ejercicio 13:
Usando las leyes del algebra de conjuntos, probar que:
a) (A ⋂ B) – C = (A – C) ⋂ (B – C)
b) ( A ⋂ B) ⋃ (∁A ⋂ B) ⋃ (A ⋂ ∁B) = A ⋃ B
a) (A ⋂ B) – C =
(A – C) ⋂ (B – C)
(A ⋂ B) – C = (A
⋂ B) ⋂ ∁C [Teorema]
=
( A ⋂ B) ⋂ ( ∁C ⋂ ∁c) [Idempotencia]
=
A ⋂ ( B ⋂ ∁C) ⋂ ∁C
[Asociativa]
=
A ⋂ (∁C ⋂ B) ⋂ ∁C
[Conmutativa]
=
(A ⋂ ∁C) ⋂ (B ⋂ ∁C) [Asociativa]
=
(A – C) ⋂ (B –C) [Teorema]
b)( A ⋂ B) ⋃ (∁A ⋂ B) ⋃ (A ⋂ ∁B) = A ⋃
B
( A ⋂ B) ⋃ (∁A ⋂ B) ⋃ (A ⋂ ∁B) = [(A ⋂ B) ⋃ ( ∁A ⋂ B) ⋃ (A ⋂ ∁B) [Asociativa]
= [(A ⋃ ∁A) ⋂ B] ⋃ (A ⋂ ∁B) [Distributiva]
= (U ⋂ B) ⋃ (A ⋂ ∁B) [Complementación]
= B ⋃ (A ⋂ ∁B) [Identidad]
= (B ⋃ A) ⋂ (B ⋃ ∁B) [Distributiva]
= (B ⋃ A) ⋂ U [Complementación]
= B ⋃ A [Identidad]
= A ⋃ B [Conmutativa]
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