We introduce the notion of cyclic flats for q-matroids. By expressing the rank function of the q-matroids in terms of the cyclic flats and their rank values, we obtain that the cyclic flats together with their rank values fully determine the q-matroids. Next we show that the cyclic flats of the direct sum of two q-matroids are exactly all the direct sums of the cyclic flats of the two summands. This simplifies the rank function of the direct sum significantly. A q-matroid is called irreducible if it cannot be written as a (non-trivial) direct sum. We provide a characterization of irreducibility in terms of the cyclic flats and show that every q-matroid can be decomposed into a direct sum of irreducible ones, which are unique up to equivalence.

翻译：我们引入了q-拟阵中循环平面的概念。通过用循环平面及其秩值表示q-拟阵的秩函数，我们得到循环平面及其秩值完全决定了q-拟阵。接着我们证明，两个q-拟阵直和的循环平面恰好是两个被加项循环平面的直和。这显著简化了直和的秩函数。如果一个q-拟阵不能写成（非平凡）直和，则称之为不可约的。我们给出了基于循环平面的不可约性刻画，并证明了每个q-拟阵都可以分解为不可约q-拟阵的直和，且该分解在等价意义下唯一。