The fact that CCP is intractable (coNP-complete) means that there exist difficult problem instances that take exponential time in the worst case, while efficient algorithms for CCP exist when the number of policies is not too large.
It may be noted that a secreted form of Testican-1 protein, if it exists, may be difficult to detect using IHC.
Vulcanoids, should they exist, would be difficult to detect due to the strong glare of the nearby Sun, and ground-based searches can only be carried out during twilight or during solar eclipses.
Addressing specific differences in the intervention received by patients between the models, if they exist, may be difficult.
The consideration of trade-offs is a valuable part of applied evolutionary biology but evolutionarily unbreakable trade-offs, if they exist, can be difficult to confirm.
In addition to the overall dearth of nutrition and physical activity regulations related to obesity, the regulations that do exist may be difficult to interpret by child care providers.
Logistic regression analysis proved that a strong association exists between difficult behaviors at 3 and 6 months: the likelihood of difficult behaviors at the age of 6 months increased more than five times (OR = 5.29; 95% CI 2.53-11.00; p < 0.001) if such problems were reported at the age of 3 months.
However, characterising ecologically significant functional variation in wild species for which no closely related model organism exists remains difficult, and is further complicated in species which are subject to active conservation programs due to restrictions against invasive sampling.
Although the risk of unintended consequences always exists and difficult to predict, Smith [ 46] and Marshall [ 47] identified a number of ways in which potential unintended consequences may be reduced.
The treatment of oxidative stress during the short effective therapeutic window that exists is difficult; injury caused by free radicals may well occur before a patient can receive effective treatment [ 50].
