Since every formula in the antecedent (the left side) must be true to conclude the truth of at least one formula in the succedent (the right side), adding formulas to either side results in a weaker sequent, while removing them from either side gives a stronger one.
因为在（左边的）的前件中的所有公式都必须为真来获得在（右边的）后继中至少一个公式为真，向任何一端增加公式都导致一个更弱的相继式，而从任何一端去除公式都得到更强的相继式。