Optimization can favor parameter values that fit the objective yet become excessively large. Regularization adds an element to the loss function that steers optimization toward more desirable parameter values. section 2.3.4
L2 regularization adds a term proportional to the sum of squared parameter values. Because squaring amplifies larger values, the penalty discourages excessively large parameter estimates. section 2.3.4
L2-regularized objective
Replace a loss such as negative log-likelihood with negative log-likelihood plus a term proportional to Σθᵢ². Optimization then balances fit against parameter magnitude. section 2.3.4












