Theorem ex202 ≪ | index | src | ≫ 

theorem ex202 (R: set) (l: nat): $ ~l, 0 e. ex2 R $;
StepHypRefExpression
1
 
0, l e. ex2 (cnv R) <-> l, 0 e. ex2 R
2
 
~0, l e. ex2 (cnv R)
3
1, 2
 
~l, 0 e. ex2 R

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp, itru), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_10, ax_11, ax_12), axs_set (elab, ax_8), axs_the (theid, the0), axs_peano (peano1, peano2, peano5, addeq, muleq, add0, addS, mul0, mulS)