The phrase "a complex and vast" is correct and usable in written English.
It can be used to describe something that is intricate and extensive in nature, often referring to ideas, systems, or subjects.
Example: "The universe is a complex and vast entity, filled with mysteries that scientists are still trying to unravel."
Alternatives: "an intricate and extensive" or "a complicated and expansive".
Atopic dermatitis is a complex and multifactorial disease, and despite the vast research efforts, its pathogenesis has not been entirely elucidated yet.
Background: The human intestine is host to an enormously complex, diverse, and vast microbial community the gut microbiota.
For nascent innovators who aspire to creatively impress upon and uplift the lives of those less privileged, 'social innovation' can seem like an underground movement in a fascinating new city: complex, inaccessible, and vast.
Defining the self philosophically, and even linguistically, has a complex history and a vast literature (see e.g., Taylor 1989; Seigel 2005; Martin and Barresi 2006).
And in the nineteenth century Britain's East India Company, in one of the most successful acts of industrial espionage ever, sent a botanist to China, where he stole both the technique for processing tea leaves (which is surprisingly complex) and a vast collection of tea plants.
Google is, after all, an algorithm (albeit a very complex, intelligent, successful and vast algorithm).
As Olivia Judson (2008) recently commented, terms like "Darwinism" "suggest a false narrowness to the field of modern evolutionary biology, as though it was the brainchild of a single person 150 years ago, rather than a vast, complex and evolving subject to which many other great figures have contributed".
If so, how do we explain the treatment of Kamel Bourgass, a loner and misfit whose case was nonetheless blown up into a vast, complex and dangerous al-Qaida plot to poison the Tube with ricin in 2003?
Arguing that the submarines will not be made obsolete, he said: "The ocean is a vast, complex and challenging environment in which to conduct large-scale anti-submarine warfare.
The reality is that Africa is a vast, complex and complicated place that has been so reduced in the global imagination that most people have no real idea of its true proportions any more.
