EXHIBIT 21.1 List of Subsidiaries 1. Summit Design (EDA) Ltd., an Israeli Corporation. 2. Summit Verification, Inc., a Delaware Corporation. 3. ProSoft Oy, a Finnish Corporation. 4. Summit Design France, a French Corporation. 5. Summit Design, GmhH, a German Corporation. 6. Innovative Software, Inc., a Delaware Corporation. 7. Viewlogic Systems, Inc., a Delaware Corporation.