“…On the other hand, when the HFT agent has a short position, which means the agent short-sells the asset, its buy and sell order prices are set higher so that its buy order matches an order from normal agents easier than its sell order [55], [56]. Let the base spread of the HFT agent and the coefficient of its position (its initial value is set based on Kusaka et al [55] as 5.0 × 10 −8 ) be θ h and w h . Let the best-bid, the best-ask, its basic order price, its buy order price, its sell order price at time t, and the HFT's position between time t and t + 1 be P t bb , P t ba , P t bv,h , P t bo,h , P t so,h , and s t h , respectively.…”