n.
a difficult problem
同义词：conundrumenigmabrain-teaser
a coarse sieve (as for gravel)
Riddling/remuage machine
On riddling and weak attractors
On riddling and weak attractors
Remuage - riddling machine
Riddling Bifurcation in Chaotic Dynamical Systems
Noise-Induced Riddling in Chaotic Systems
Riddling and invariance for discontinuous maps preserving Lebesgue measure
Global properties of symmetric competition models with riddling and blowout phenomena
Influence of the use of bentonite as a riddling agent on foam quality and protein fraction of sparkling wines (Cava)
BIFURCATIONS ANALYSIS OF POPULATION INVASION: ON–OFF INTERMITTENCY AND BASIN RIDDLING
