diff --git a/lectures/lecture3_dafny.pdf b/lectures/lecture6_dafny.pdf similarity index 100% rename from lectures/lecture3_dafny.pdf rename to lectures/lecture6_dafny.pdf diff --git a/lectures/lecture5_isabelle.pdf b/lectures/lecture7_isabelle.pdf similarity index 100% rename from lectures/lecture5_isabelle.pdf rename to lectures/lecture7_isabelle.pdf diff --git a/lectures/lecture6_isabelle2.pdf b/lectures/lecture8_isabelle2.pdf similarity index 100% rename from lectures/lecture6_isabelle2.pdf rename to lectures/lecture8_isabelle2.pdf