“Clear and lucid” poems from a US Poet Laureate and Pulitzer Prize winner who “journeys through the landscape of memory, consciousness, loss, and love” (The Washington Post). Kay Ryan is acclaimed for her highly relatable, deeply insightful poems. Erratic Facts is her first new collection since the Pulitzer Prize–winning The Best of It, and it is animated with her signature swift, clearheaded, lyrical style. At once witty and melancholy, playful and heartfelt, Ryan examines enormous subjects—existence, consciousness, love, loss—in compact poems that have immensely powerful resonance. Her sly rhymes and strong cadences convey both musicality and wisdom. While these pieces are composed of the same brevity and vitality that have characterized her singular voice over the course of more than twenty years, her imagination is more eccentric and daring than ever. Erratic Facts solidifies Ryan’s place at the pinnacle of American poetry. “Read a poem once and take in its crisp rhythms, subtle rhymes, and arresting images. Read it again and detect its hide-and-seek metaphors and meanings. . . . [Ryan’s] quantum poems pose resonant questions of physics and metaphysics, of attentiveness and caring on scales intimate and universal.” —Booklist

1 The Importance of Irreversibility and Learning - Familiar 11 Bxamples Revisited 1. 1 Neoclassical Investment Models: A Brief Survey 11 1. 1. 1 The Standard Neoclassical Investment Theory Model 13 1. 1. 2 The Investment Model with Adjustment Costs 15 1. 1. 3 The Irreversibility of Investment 17 1. 1. 4 Delivery Lags 18 1. 2 Flexible Manufacturing Systems 22 1. 2. 1 Some Basic Facts about Manufacturing 23 1. 2. 2 The Determinants of the Flexibility of Manufacturing Systems 25 1. 2. 3 Manufacturing as a Multiperiod Choice Problem 28 1. 3 Conclusions 30 2 The Role of Irreversibility and Learning in Sequential Decision Problems - Basic Concepts 33 2. 1 The Two-Period Model without Uncertainty 33 2. 1. 1 The Elements of the Model 34 2. 1. 2 Economic Examples 37 2. 1. 3 Some Basic Results 39 2. 1. 4 Intertemporal Opportunity Costs 42 2. 2 The Two-Period Model with Uncertainty 46 2. 2. 1 The Elements of the Kodel 46 2. 2. 2 Special Cases 50 2. 2. 3 Flexibility and the Value of Information 54 2. 2. 4 An Example: Waiting to Invest 56 2. 3 Switching Costs 59 2. 3. 1 The Extended Model 59 2. 3. 2 An Example: Money Demand as Demand for Flexibility 61 2. 4 Summary and Outlook 63 3 Determinants of the Optimal Choice in Sequential Decision Problems - The Two-Period Case 65 3. 1 The Formulation of the Problem 66 3. 1.