Theorem lmemsnoc | index | src |

theorem lmemsnoc (a b x: nat): $ x IN a |> b <-> x IN a \/ x = b $;
StepHypRefExpression
1 bitr
(x IN a |> b <-> x IN a \/ x IN b : 0) -> (x IN a \/ x IN b : 0 <-> x IN a \/ x = b) -> (x IN a |> b <-> x IN a \/ x = b)
2 lmemappend
x IN a ++ b : 0 <-> x IN a \/ x IN b : 0
3 2 conv snoc
x IN a |> b <-> x IN a \/ x IN b : 0
4 1, 3 ax_mp
(x IN a \/ x IN b : 0 <-> x IN a \/ x = b) -> (x IN a |> b <-> x IN a \/ x = b)
5 lmem1
x IN b : 0 <-> x = b
6 5 oreq2i
x IN a \/ x IN b : 0 <-> x IN a \/ x = b
7 4, 6 ax_mp
x IN a |> b <-> x IN a \/ x = b

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)