Theorem divltmul1 | index | src |

theorem divltmul1 (a b c: nat): $ b != 0 -> (a // b < c <-> a < b * c) $;
StepHypRefExpression
1 ltnle
a // b < c <-> ~c <= a // b
2 ltnle
a < b * c <-> ~b * c <= a
3 ledivmul1
b != 0 -> (c <= a // b <-> b * c <= a)
4 3 noteqd
b != 0 -> (~c <= a // b <-> ~b * c <= a)
5 2, 4 syl6bbr
b != 0 -> (~c <= a // b <-> a < b * c)
6 1, 5 syl5bb
b != 0 -> (a // b < c <-> a < b * c)

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)