The phrase "assumed false" is correct and usable in written English.
It can be used in contexts where a statement or proposition is taken to be untrue or not valid without proof.
Example: "In the context of the debate, the hypothesis was assumed false until further evidence could be presented."
Alternatives: "presumed incorrect" or "taken as untrue".
The authorities said that of the three couples, all but Ms. Peláez had assumed false identities.
The authorities said that of the three couples, all but Ms. Pel? had assumed false identities.
Some of the accused assumed false names and backgrounds – in one case stealing the identity of a dead Canadian.
From there, they made their way to Canterbury, where they assumed false identities as Tim and Julia Holte, two married Canadian students at the University of Kent.
Agency employees assumed false identities and exchanged messages with real American political activists, who offered them tips, such as focussing on "purple states like Colorado, Virginia, and Florida".
The Smileys, who had worked for the city and lived in Jamaica Estates, Queens, defied the court order to return the baby to his biological parents, fled the state, assumed false identities and started a new life, selling crafts in Albuquerque.
Until recently, we had no satisfying explanation for the 3 assumed false-positive results.
As mentioned before, the observed intermittent shedding may be explained by the relatively poor sensitivity of culture methods and we therefore corrected for the occasional assumed false-negative result.
Undercover officers assume false identities to blend in on the street and often buy drugs and guns.
The narrator and his activist parents abscond to the city's outskirts, where they assume false identities.
Cummings studied at the Carnegie Institute of Technology and Drury College before assuming false identities in order to become an actor.
