The phrase "an extremely complex problem" is correct and usable in written English.
You can use it when describing a situation or issue that is very intricate and difficult to understand or solve.
Example: "The researchers faced an extremely complex problem that required innovative solutions and extensive collaboration."
Alternatives: "a highly complicated issue" or "a very intricate challenge."
But when a large number of computers are linked together to deal with an extremely complex problem, there may simply be too much data to store.
Describing how data would flow through a network was an extremely complex problem, but Kleinrock knowingly made the simplifying and inaccurate assumption that the time when data arrived at a node and the time the node spent processing the data were independent of each other.
The issue of child labor in the production of hybrid cotton is an extremely complex problem that has existed for many, many years in India.
Detailed production scheduling is an extremely complex problem (Brucker 2007) wherein most cases are considered NP-hard (Günther and van Beek 2003).
The design of a general post-processor capable of translating the output of multiple robot simulators to multiple robot programming languages is an extremely complex problem.
While deploying MRs and IGWs, intricate relationships among antenna types, wireless links with adaptive modulation and coding, MAC scheduling, routing, and equipment cost render the network planning an extremely complex problem.
Individuals, corporations and governments constantly face the extremely complex problem of ordering and prioritizing their numerous decisions according to urgency and importance.
This simultaneous optimization problem was defined as an extremely complex optimization problem [18].
Similar to the classical HMM, the likelihood expression of Equation 1 leads to an extremely complex optimization problem with seemingly impossible direct solution.
However, bonding plates to RC structures is an extremely complex engineering problem as research has shown that bonded plates are prone to about 30 mechanisms of failure.
Regardless of this, the above-mentioned question relates to an extremely complex ethical problem, which must be addressed on broader grounds.
