diff --git a/bv/uebung12_presence.txt b/bv/uebung12_presence.txt
new file mode 100644
index 0000000..e2a300f
--- /dev/null
+++ b/bv/uebung12_presence.txt
@@ -0,0 +1,4 @@
+O_5 = step_0 (W_35*H_3 + W_45*H_4)
+= step_0(W_35 * step_0(I_1*W_13 + I_2*W_23) + W_45 * step_0(I_1 W_14 + I_2 W_24))
+= step_0(4 * step(2*3 + 4*1) + 1 * step_0(2 * 1 + 4 * (-3)))
+= step_0(4 * step(10) + step_0(-10)) = step_0(4) = 1