diff --git a/slides/BLcourse4.key b/slides/BLcourse4.key
index 3f69408eb853c863a0c459cd20dc49791a3681f5..b8603e5cee4081f35a00679c1349e9772e0a68b5 100755
Binary files a/slides/BLcourse4.key and b/slides/BLcourse4.key differ
diff --git a/slides/BLcourse4.pdf b/slides/BLcourse4.pdf
index d9cb622c87fd50f6b8881267996ab6263d24604c..b1bd9416446b14f350252d400dcc4b24349bca86 100644
Binary files a/slides/BLcourse4.pdf and b/slides/BLcourse4.pdf differ