In homologous recombination (Holliday model), the last process i.e resolution can occur in two ways (horizontl and vertical cuts) leading to formation of either "splice" or crossover products or "patch" or non-crossovers product (as shown in the image). The two possible products confuse me with what are crossovers. I could not understand why the "patch" product (Fig. (g) in the image) is called a non-crossover. Is it because one strand of both the homologous helices are same? Also please do explain what is the hetero-duplex in this model?