# What is the impact of making flow fractional rather than integer?

When creating a network flow formulation you can set up sinks with integer flow requirement $$\ge 1$$. This yields solutions with the total amount of flow along an edge.

I have also seen this as a real positive number between $$0$$ and $$1$$, the latter inclusive (i.e. $$(0,1]$$). Derived by dividing the sink demand by the total demand.

What are the benefits of the approaches or are they considered equivalent?

• So you are not asking about requiring integer demands vs allowing demands to be fractional; but rather leaving demands in units vs normalizing them so they are all in [0,1], correct? – LarrySnyder610 Jun 14 '19 at 16:22
• @LarrySnyder610 yes correct – fhk Jun 14 '19 at 16:34
• Do you have some references? When changing only units the models are equivalent, and that should make no difference in solving time. Looks like a question of preference or convenience in modeling. – Marcus Ritt Jun 14 '19 at 23:31