The phrase "are difficult to represent" is correct and usable in written English.
You can use it when discussing concepts, ideas, or phenomena that are challenging to depict or illustrate in a particular form, such as visually or mathematically.
Example: "The emotions conveyed in the painting are difficult to represent in words, as they evoke a deep sense of nostalgia."
Alternatives: "are hard to depict" or "are challenging to illustrate".
Hydrologic data sets such as precipitation records typically feature complex geometries that are difficult to represent as a whole using classical stochastic methods.
Real-world scheduling problems are intrinsically complex because of the dynamic nature of industrial environments, conflicting organizational goals, the existence of operational constraints and preferences that are difficult to represent in a computational model.
Numerical considerations lead us to solve for F, instead of f, since delta functions are difficult to represent in floating point, while the initial conditions for F, the Heaviside step function, H ( x ), faces no such difficulties [24].
Analysis of renewable utility integration, such as solar thermal or photovoltaics, introduces several obstacles for established methods: the time-dependency of resources, storage inertia and losses, and intrinsic non-linearities of the system performance are difficult to represent by linearized, time-invariant MILP equations.
Abbreviations are also a persistent problem, since many structures are difficult to represent in a human-readable way without abbreviating certain groups, but since there is no universal repository for abbreviations, and many research groups invent their own overlapping sets for localised use, it is necessary to have a way to define these internally as part of the structure definition.
Some taiko pieces, such as Yatai-bayashi, include patterns that are difficult to represent in Western musical notation.
Umbrella bodies intended to act as interlocutors with governments, such as the Muslim Council of Britain (MCB) and the French Council for the Muslim Faith (CFCM), are rejected by many Muslims for being too political, or not political enough, or simply not representative of people who may be difficult to represent, or may not want to be represented as "Muslims".
"It is difficult to represent someone in absentia," conceded Michael B. Himmel, a lawyer from Woodbridge who is defending Mr. Axelrod in the tax case.
Critics would say it's difficult to represent modern Britain or guarantee cognitive diversity when you've all had been hanging out in the same student union bars.
"It's difficult to represent a friend," Mr. Richman said, "because the lines of friendship and professionalism blur, and you can't let that happen.
This structure is difficult to represent in a two-dimensional picture, but Figure 7A is a useful analogue with the hollow circles representing oxygen atoms and the small solid dots representing silicon atoms.
