Issue Description

For the appended input the output is correct, but not fully minified. Right now it seems like the bug is within the Quine-McCluskey implementation, more specifically in the way it deals with don't-care fields (X) and the number of different columns between two rows that of which at least one contains a don't-care field.

E.g. the two rows

I7 I6 I5 I4 I3 I2 I1 I0 O1
0 1 X X X X X X 1
1 X X X X X X X 1

should result in I7 + I6 not in !I7 * I6 + I7.

Input

I7 I6 I5 I4 I3 I2 I1 I0 O1
0 0 0 0 0 0 0 0 0 
0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 1 X 0
0 0 0 0 0 1 X X 1
0 0 0 0 1 X X X 1
0 0 0 1 X X X X 0
0 0 1 X X X X X 0
0 1 X X X X X X 1
1 X X X X X X X 1

Output

Current Version

O1 = !I7 * !I6 * !I5 * !I4 * !I3 * I2 + !I7 * !I6 * !I5 * !I4 * I3 + !I7 * I6 + I7

Table format

I7 I6 I5 I4 I3 I2 I1 I0 O1
0 0 0 0 0 1 X X 1
0 0 0 0 1 X X X 1
0 1 X X X X X X 1
1 X X X X X X X 1

Desired

O1 = I7 + I6 + !I5 * !I4 * I3 + !I5 * !I4 * I2

Issue description

The current implementation does not remove non-essential prime implicants. A final processing of the output table with the Petrick's method (https://en.wikipedia.org/wiki/Petrick%27s_method) would minify all remaining prime implicants properly.

Example input

Example input resulting in an output that is not entirely minified.

D C B A X
0 0 0 0 0
0 0 0 1 1
0 0 1 0 1
0 0 1 1 1
0 1 0 0 0
0 1 0 1 1
0 1 1 0 0
0 1 1 1 0
1 0 0 0 0
1 0 0 1 0
1 0 1 0 1
1 0 1 1 1
1 1 0 0 0
1 1 0 1 1
1 1 1 0 0
1 1 1 1 0

Output comparison

Screenshot

Second example (from Wikipedia)

C B A X
0 0 0 1
0 0 1 1
0 1 0 1
0 1 1 0
1 0 0 0
1 0 1 1
1 1 0 1
1 1 1 1