Groups consider preschool measure REINER TO PROMOTE HIS INITIATIVE IN S.J. Rob Reiner returns to San Jose on Thursday to pitch Proposition 82, his Preschool for All Act, as two key Silicon Valley business groups wrangle over whether to endorse the plan to provide a free voluntary year of preschool to all 4-year-olds in the state. The tech-heavy Silicon Valley Leadership Group, which met with Reiner in mid-December, and the San Jose Silicon Valley Chamber of Commerce have yet to weigh in on the complex initiative, which goes before voters statewide June 6. In recent weeks, a variety of opponents...