ResearchGate

You are about to leave ResearchGate.

Click to proceed to:

http://dx.doi.org/10.3934/math.20221101

.no-javascript-warning { border: 1px solid #FAC8AF; background-color: #FADECF; margin: 0; padding: 10px 15px; text-align: center; position: fixed; bottom: 0; left: 0; right: 0; z-index: 10; } .no-javascript-warning__message { padding: 10px; }

For full functionality of ResearchGate it is necessary to enable JavaScript. Here are the instructions how to enable JavaScript in your web browser.