b 1 0 = 0 , b 2 0 = 0

For r = 1 to T do

c 1 r , c 2 r = softmax ( b 1 r 1 , b 2 r 1 )

s r = c 1 r u 1 + c 2 r u 2

a r = S q u a s h ( s r )

b i r = b i r 1 + a r u i