![A,B] = ([!A,B] + [A,!B] + [!A,!B])

This is wrong:
!(D1+D2) = !D1 + !D2

!(D1+D2) = !D1 * !D2

Add:
!D1*D2 = !D1 + !D2

!(D1.D2) = !D1 . D2 + D1 . !D2 // not correct

The following not correct either:
!(D1.D2) = !D1 . D2 + D1 . !D2 + [Source(D1),!Target(D1)].[!Target(D1),Target(D2)]

!([A,B].[B,C]) = ![A,B].[B,C] + [A,B].![B,C]
= ([!A,B] + [A,!B] + [!A,!B]).[B,C] + [A,B].([!B,C] + [B,!C] + [!B,!C]) 

= [!A,B].[B,C] + [A,B].[B,!C] // miss: + [A,!B].[!B,C]
= [!A,B].[B,C] + [A,B].[B,!C] + [A,!B].[!B,C]
=

negation of negation:
!![A,B] = !([!A,B] + [A,!B] + [!A,!B])
= ![!A,B] + ![A,!B] + ![!A,!B]
= [A,!B] + [!A,B] + [A,B] // something wrong with union?

Recheck:
!![A,B] = !((([!A,B] + [A,!B]) + [!A,!B]))
= !([!A,B] + [A,!B]) * ! [!A,!B]
= ![!A,B] * ![A,!B] * ! [!A,!B]
= ([A,B] +[!A,!B] [A,!B]) * ([!A,!B]+[A,B]+[!A,B])*([A,!B]+[!A,B]+[A,B])
= (... + [A,B] + ...) * (... + [A,B] + ...) * (... + [A,B] + ...)
= [A,B]


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