Table 2. Contingency table of partitions P and P′, with labelings r and s.

	$P_1^{\prime }$	$P_2^{\prime }$	...	$P_S^{\prime }$	sum
P1	c11	c12	...	c1S	a1
P2	c21	c22		c2S	a2
	...			...
PR	cR1	cR2	...	cRS	ar
Sum	b1	b2	...	bS	n = ∑cij