DBSCAN ALgorithm

Which of the following statement about DBSCAN algorithm is false?

• Can find arbitrarily shaped clusters

• No need to specify number of clusters

• Robust to outliers

• Not sensitive to parameters

A point is said to be core point if

• the $\epsilon$ neighbourhood of the point contain more than or equal minpts

• the $\epsilon$ neighbourhood of the point contain less than minpts

• the $\epsilon$ neighbourhood contain less than minpts but is in neighbourhood of a core point

• None

A point is said to be Border point  if

• the $\epsilon$ neighbourhood of the point contain more than or equlal  minpts

• the $\epsilon$ neighbourhood of the point contain less than minpts

• the $\epsilon$ neighbourhood contain less than minpts but is in neighbourhood of a core point

• None

Given the the Radius (R) as marked in the figure and the minpts = 6. Then the red point in the figure is a ___________

• Core point

• Border point

• Neither core nor border point

• Can't say

Which of the following statement is false?

• A point q is directly reachable from p , if q is distance $\epsilon$ from the core point p

• A point q is directly reachable from p , if q is distance $\epsilon$ from any point p

• Points are only said to be directly reachable from core points

• A point q is reachable from p, if there is a path p1,p2,p3....pn, where p1 = p, pn = q and $p_{\left(i+1\right)}$ directly reachable from $p_i$

Which of the following informations are used by OPTICS algorithm to store the cluster ordering

• Core distance and Reachability distance

• Core distance and Radius

• Core distance and Minpts

• Reachability distance and Radius

From the given figure identify the core distance of point p. Given the value of  $\epsilon^{'\ }$  = 3mm

• 3 mm

• 6 mm

•  $dist\left(p,q_1\right)$  

• None

From the given figure identify the reachability  distance to the point  $q_1$  from point p. Given the value of  $\epsilon^{'\ }$  = 3mm

• 3 mm

• 6 mm

•  $dist\left(p,q_1\right)$  

• None

From the given figure identify the reachability  distance to the point  $q_2$  from point p. Given the value of  $\epsilon^{'\ }$  = 3mm

• 3 mm

• 6 mm

•  $dist\left(p,q_1\right)$  

•  $dist\left(p,\ q_2\right)$  

Which of the following statement about OPTICS algorithm is false?

• OPTICS is an extension of DBSCAN

• OPTICS provides an ordering of points to identify clustering structure

• OPTICS is good for interactive cluster analysis

• In the reachability plot deeper valley indicates that the cluster is not dense.