====== Vierfeldertafel ======

^                ^   $ A$                       ^    $\bar A$                       ^                    ^
^ $B$         |  $P(A \cap B)$          |  $P(\bar A \cap B)$          |  $P(B)$        |
^ $\bar B $ | $ P(A \cap \bar B $)  | $P(\bar A \cap\bar  B )$  | $P(\bar B )$ |
^                 | $P(A)$                      |  $P(\bar A )$                   |       $1$         |

Dabei gilt:\\
$ P(A\cap B)=P(A)\cdot P_A(B) $\\
$ P(A\cap \bar B)=P(A)\cdot P_A(\bar B) $\\
$ P(\bar A\cap B)=P(\bar A)\cdot P_{\bar A}(B) $\\
$ P(\bar A\cap \bar B)=P(\bar A)\cdot P_{\bar A}(B) $\\