Table 3 Best equation obtained by PySR using ln(1-R), where x₀, x₁, and x₂ represent lnΔK, ln(1-R), and ln(1-ΔK_th/ΔK), respectively

1

0

\(- 16.64\)

3

0.506034

\(x_{0} - 18.65\)

4

1.015250

\(- \ln (\left| {x_{2} } \right|) - 17.52\)

5

5.138852

\({{ - 0.79} \mathord{\left/ {\vphantom {{ - 0.79} {x_{2} }}} \right. \kern-0pt} {x_{2} }} - 20.06\)

6

7.903765

\(- 2.78{ \times }\ln (\left| {x_{2} } \right|) - 19.08\)

8

1.355014

\(- 3.66{ \times }\ln (\left| {x_{2} } \right|) - x_{2} - 20.76\)

10

1.515445

\(- 3.33{ \times }\ln (\left| {x_{2} } \right|) - 0.62{ \times }x_{2} - 20.12\)

11

1.196780

\(\ln (\left| {x_{2} } \right|){ \times ((} - 0.31{ \times }\ln (\left| {x_{2} } \right|)) + 2.38) - 19.44\)

12

1.091710

\({{{ - 4}{.43}} \mathord{\left/ {\vphantom {{{ - 4}{.43}} {(x_{0} - }}} \right. \kern-0pt} {(x_{0} - }}x_{2} ) - 2.79{ \times }\ln (\left| {x_{2} } \right|) - 17.41\)

14

1.204919

\({{{( - 6}{.19 - }x_{1} )} \mathord{\left/ {\vphantom {{{( - 6}{.19 - }x_{1} )} {(x_{0} - }}} \right. \kern-0pt} {(x_{0} - }}x_{2} ) - 2.80{ \times }\ln (\left| {x_{2} } \right|) - 16.90\)

16

0.264973

\({{{6}{.19}} \mathord{\left/ {\vphantom {{{6}{.19}} {(x_{0} - }}} \right. \kern-0pt} {(x_{0} - }}x_{2} ) - 0.44{ \times }x_{1} - 2.80{ \times }\ln (\left| {x_{2} } \right|) - 16.90\)

17

1.166901

\({{ - 0.02} \mathord{\left/ {\vphantom {{ - 0.02} (}} \right. \kern-0pt} (}x_{1} + 0.58){ \times }(0.31{ \times }\ln (\left| {x_{2} } \right|) - 2.38) + \ln (\left| {x_{2} } \right|) - 19.39\)

19

0.016524

\({{ - 0.02} \mathord{\left/ {\vphantom {{ - 0.02} (}} \right. \kern-0pt} (}x_{1} + 0.59){ \times }(0.31{ \times }\ln (\left| {x_{2} } \right|) - 2.38) - 0.02 + \ln (\left| {x_{2} } \right|) - 19.39\)