Correction: Theoretical study of the effect of ports in the formation of city systems

Correction to: Journal of Shipping and Trade 2022, 7(1):16 https://doi.org/10.1186/s41072-022-00117-6

Following publication of the original article [1], some numbers and letters were wrongly placed in the equations (1) and (2) under the heading Krugman’s formulation due to typesetting errors.

The equations currently show:

$$\begin{aligned} & \overline{P}_{i} =^{{\text{X}}} P_{k} \left( t \right)/{9} \\ & k \in\Omega \\ \end{aligned}$$

(1)

$$V_{{i{1}}} \left( t \right) = K_{{1}} * \overline{P}_{i} \left( t \right) - \beta$$

(2)

The equations should show:

$$\bar{P}_{i} = \sum\limits_{k \in \Omega } {P_{k} \left( t \right)/9}$$

(1)

$$V_{i}^{1} \left( t \right) = K_{1} * \bar{P}_{i} \left( t \right)^{ - \beta }$$

(2)

The original article [1] has been corrected.