Evolutionary Computation Techniques for Predicting Atmospheric Corrosion

Table 4

The best five expressions obtained for the corrosion expression of steel using the GP. The fitness of an expression is its mean squared error (MSE), and its size is the number of nodes in its underlying abstract-syntax tree.

Rank	Size	MSE	𝑅	Expression
1	31	788	0.87523	𝑇+41𝐸+1063TOWCl^−+1007𝐸^225+SO263TOW+1007𝐸+257𝑇TOW𝐸^225SO2
2	41	810	0.87348	𝑇+11𝐸5+31𝐸^210SO2+8𝐸SO2+(11/5)+2569TOW𝑇+SO2+(83Cl^−/100)−61005
3	27	831	0.87038	𝑇+3TOWSO2+Cl^−5+3𝐸3SO2/5+3𝑇𝐸/5SO2+(13/5)5+1710
4	49	1036	0.85825	𝑇+SO2−2SO2−Cl^−𝐸−TOW+3+𝐸^2+23TOWSO2𝐸+5023TOW37SO2/10−(37𝑇/10)+10TOW𝐸(𝑇−(13/10))100SO2
5	69	878	0.83984	57SO2(100−𝐸+7TOWTOW+23Cl^−/50)−SO2−23SO2𝐸/5/𝑇5+()×()+𝐸+𝑇TOW𝐸+TOW𝐸+6𝐸/256𝐸SO2−23SO2𝐸/5/𝑇−3SO2+(21/5)/25SO2