theorem zltletr (a b c: nat): $ ab <=Z c -> a
Step Hyp Ref Expression 1 zletr b <=Z c -> c <=Z a -> b <=Z a2 1 conv zle b <=Z c -> ~a <Z c -> ~a <Z b3 2 con4d b <=Z c -> a <Z b -> a <Z c4 3 com12 a <Z b -> b <=Z c -> a <Z cAxiom 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)