Confused with eq(8)

[CharlesGong12]

Hi, thanks for your excellent work! In eq(7), 𝑐_t′ = Concat(𝜆 ∗ 𝑐_𝑙′ , 𝑐_𝑡 ). In eq(8), 𝑥 = CA(𝑥, 𝑐_𝑡′ ). Thus x should be CA(𝑥, Concat(𝜆 ∗ 𝑐_𝑙′ , 𝑐_𝑡 ) ). But in the paper, x in eq(8) is assigned as 𝜆 ∗ CA(𝑥, 𝑐_𝑙 ) + CA(𝑥, 𝑐_𝑡 ). I have 2 questions:

1. Why can the concat operation become an add operation?
2. Why does 𝑐_𝑙′ become 𝑐_𝑙？
3. How deep is your CAM?