```xml
<!-- src/Acme/BlogBundle/Resources/config/validation.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="Acme\BlogBundle\Entity\Author">
        <property name="name">
            <constraint name="Regex">
                <option name="pattern">/^[a-z]+$/i</option>
                <option name="htmlPattern">^[a-zA-Z]+$</option>
            </constraint>
        </property>
    </class>
</constraint-mapping>
```