To run Scheme-based reduction semantics:

1. Install DrScheme version 203.
2. Download reduction-semantics.plt and save it as a file.
3. Open your downloaded reduction-semantics.plt with DrScheme, and allow DrScheme to install it.
4. In DrScheme, select the Choose Language item in the Language menu. In the dialog that appears, turn down the PLT arrow and select Textual (MzScheme).
5. In DrScheme, open a reduction-semantics program (such as r.scm) and click the Execute button.