The phrase "establish a complex" is a correct and usable phrase in written English.
You can use it when describing the setting up of a large or complex system, such as an organization, structure, or process. For example, "The company took several years to establish a complex system of regulations and procedures."
Advances in MRI technology and a broad consensus on the basic imaging protocols have helped to establish a complex technology such as cardiac MRI within a relatively short period of time.
The 2004 Report of the UN Secretary General's Consultative Group on Flag State Implementation reported that "It is very easy, and comparatively inexpensive, to establish a complex web of corporate entities to provide very effective cover to the identities of beneficial owners who do not want to be known".
By targeting different substrates and being controlled by diverse regulatory mechanisms [7], MMPs establish a complex network in which different enzymes may play opposite roles.
These proteins might work cooperatively to establish a complex network of apoplast response to exogenous H2O2 in the rice seedling root, and depict the strategies of the root apoplast to oxidative challenge.
The dorsal cluster neurons (DCNs) establish a complex neurite network in the Drosophila adult optic lobes.
These tumours establish a complex relationship with the associated immune cells within the ascites, developing an immunosuppressive microenvironment elicited by macrophages.
Under his government, India established a complex system of socialist economic controls that remained in place until the 1980s.
Within days, they said, they had re-established a complex community, with a hierarchy and division of labor, in which members were assigned daily tasks.
The legislation would have established a complex mathematical formula for determining whether debtors can repay part of their debts under a court-supervised plan rather than have them dissolved.
The plan put forward by Mr. Clinton, as outlined by Israeli and Palestinian officials who have spoken with reporters here, would have established a complex mosaic of jurisdictions in East Jerusalem.
Although nominally directed by Mabel Normand — Sennett's lover and leading female star — this film establishes a complex of themes and situations that Chaplin would continue to develop through his greatest work of the '20s and '30s.
