
Rough Sets 157
= (G ∧ W ∧ T) ∨ (G ∧ W ∧ S) ∨ (G ∧ T) ∨ (G ∧ T ∧ S) ∨
(L ∧ W ∧ T) ∨ (L ∧ W ∧ S) ∨ (L ∧ T) ∨ (L ∧ T ∧ S) ∨
(C ∧ W ∧ T) ∨ (C ∧ W ∧ S) ∨ (C ∧ T) ∨ (C ∧ T ∧ S)
= (G ∧ W ∧ S) ∨ (G ∧ T) ∨ (L ∧ W ∧ S) ∨ (L ∧ T) ∨ (C ∧ W ∧ S) ∨ (C ∧ T)
= (G ∧ W ∧ S) ∨ (L ∧ W ∧ S) ∨ (C ∧ W ∧ S) ∨ (G ∧ T) ∨ (L ∧ T) ∨ (C ∧ T)
e prime im
plecants are (G ∧ W ∧ S), (L ∧ W ∧ S), (C ∧ W ∧ S ), (G ∧ T ), (L ∧ T), and (C ∧ T ).
Each of the sets {G, W, S}, {L, W, S}, {C, W, S}, {G, T}, {L, T}, and {C, T} is a minimal set of attributes
that preserves the classi cation IND
I
(A). Hence each of them is a reduct. Moreover, each of the sets
{G, T}, {L, T}, and { ...