$\sigma \left(x\right)$

$\eta \left(x\right)$

$\sigma \eta \left(x\right)$

$\omega$

$\omega$

${\omega }^2$

${\omega }^2$

a

b

a

b

b

d

b

d

d

c

d

c

c

e

c

e

e

a

e

a