Greater Than Sudoku

I've found this on http://www.killersudokuonline.com:

It can be solved easily with Z3. I've took the same piece of code I used for usual Sudoku ( https://github.com/dennis714/SAT_SMT_article/blob/master/SMT/sudoku2.py, PDF file: https://yurichev.com/writings/SAT_SMT_draft-EN.pdf ) and added this:

...

"""
Subsquares:

------------------------------
         |          |         
 1,1     | 1,2      | 1,3     
         |          |         
------------------------------
         |          |         
 2,1     | 2,2      | 2,3     
         |          |         
------------------------------
         |          |         
 3,1     | 3,2      | 3,3     
         |          |         
------------------------------
"""

# from http://www.killersudokuonline.com/puzzles/2017/puzzle-GD4hzi164344.pdf

# subsquare 1,1:
s.add(cells[0][0]>cells[0][1])
s.add(cells[1][0]>cells[1][1])
s.add(cells[2][0]cells[1][4])
s.add(cells[1][3]>cells[2][3])
s.add(cells[1][4]>cells[2][4])
s.add(cells[1][5]>cells[2][5])

# subsquare 1,3:
s.add(cells[0][6]>cells[0][7])
s.add(cells[0][7]cells[2][6])
s.add(cells[1][7]>cells[2][7])
s.add(cells[1][8]>cells[2][8])

# subsquare 2,1:
s.add(cells[3][0]cells[5][1])
s.add(cells[4][2]cells[4][4])
s.add(cells[3][4]cells[3][7])
s.add(cells[3][7]>cells[3][8])
s.add(cells[3][6]>cells[4][6])
s.add(cells[4][6]cells[6][1])
s.add(cells[6][1]cells[7][1])
s.add(cells[7][0]cells[8][0])
s.add(cells[7][2]>cells[8][2])

# subsquare 3,2:
s.add(cells[6][3]>cells[6][4])
s.add(cells[6][4]>cells[6][5])
s.add(cells[7][3]>cells[7][4])
s.add(cells[7][4]cells[8][4])
s.add(cells[8][4]cells[8][4])

# subsquare 3,3:
s.add(cells[6][7]>cells[6][8])
s.add(cells[6][7]>cells[7][7])
s.add(cells[7][7]>cells[8][7])
s.add(cells[8][7]>cells[8][8])

...

( The full file: https://github.com/dennis714/yurichev.com/blob/master/blog/sudoku_GT/sudoku_GT.py )

The puzzle marked as "Outrageous" (for humans?), however it took ~30s on my old Intel Xeon E3-1220 3.10GHz to solve it:

7 3 4 6 9 2 5 1 8
2 1 5 8 3 7 9 4 6
6 8 9 5 1 4 7 2 3
1 7 3 2 8 9 6 5 4
5 4 6 1 7 3 2 8 9
9 2 8 4 5 6 1 3 7
8 6 7 3 2 1 4 9 5
4 5 2 9 6 8 3 7 1
3 9 1 7 4 5 8 6 2

→ [list of blog posts, my twitter/facebook]

Please drop me email about any bug(s) and suggestion(s): dennis(@)yurichev.com.