[["x1", "¬x3"], ["x2", "x3"], ["x1", "x2"], ["¬x2", "x3"], ["x4", "x2"]]

[["x1", "¬x2"], ["¬x1", "x3"], ["x2", "x3"], ["x1", "¬x3"], ["¬x2", "¬x3"]]

[["x1", "¬x2"], ["¬x1", "x3"], ["x2", "x3"], ["x1", "¬x3"], ["¬x2", "¬x3"], ["x4", "x5"], ["¬x4", "x6"], ["x7", "x8"], ["¬x7", "¬x8"], ["¬x5", "x6"]]