Boruta score goes to minus infinity

Question

I'm running the Boruta algorithm with a $179\times 36$ predictor matrix and a numerical response. Most of the variables have a score going to -Inf. Should I conclude there are not important or there's a problem ?

bor <- Boruta(X,y)
> dim(X)
[1] 179  36
> bor$ImpHistory[,1]
  [1] -0.33842437  0.03724477  0.77207194 -0.15966460  0.73550293 -2.11845770 -0.28029409 -1.73339443  1.80120877 -1.22191877 -0.45272011 -0.71728205
 [13] -0.57268506 -0.48498812  0.61710237  0.58776416 -0.38667490  0.51795751  0.32422847 -1.79565022  0.26975995 -1.10919356  0.77731727 -1.10266785
 [25]  0.19157178 -1.16694014  0.53795858  0.96632680 -0.99366419 -1.22646545 -1.71817624 -0.68100802 -1.41193813 -0.18065431        -Inf        -Inf
 [37]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
 [49]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
 [61]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
 [73]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
 [85]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
 [97]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
[109]        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf        -Inf
[121]        -Inf

Answer 1

Boruta works by re-applying VIM and progressively removing attributes which seem irrelevant; when an attribute becomes removed, it obviously stops getting importance scores so they are set to -Inf in the ImpHistory matrix.

Though the result of Boruta is the classification into confirmed/tentative/rejected variables; the importance history is just a side result intended for visualisation.