Final answer:
In LP, the assumption that allows variables to take any fractional value is known as 'continuous variables.' This broadens the potential solution space in contrast to Integer Linear Programming where variables must be integers.
Step-by-step explanation:
In Linear Programming (LP), the assumption that variables do not have to be integer-valued and may take on any fractional value is called continuous variables. This is in contrast to Integer Linear Programming (ILP), where variables are restricted to integer values.
The use of continuous variables allows for a greater solution space and can simplify the mathematical processes involved, though the choice of symbols and formula creation is arbitrary and serves to capture the underlying concept.