I came across a equation for kinematic chain (for lower pairs only) :

L = 2P-4

where L: Number of Links; P is the number of pairs

how could this equation be derived ?

EDIT: I tried putting values in the equation.Since for the pairs to be any integer the links can only be an even number(can be verified from the formula).

FOR

• L=4 ; P=4
• L=6 ; P=5
• L=8 ; P=6

Question 1:How to visualize kinematic chain with (6links;5 pairs) or (8L;6P)(with the help of diagram)

Question 2: Why is it the number of pairs not equal to number of links and why is it decreasing gradually from the number of links ?