Andrei Markov proved his memoryless chain to win an argument and demonstrated it on a poem. A century on, the same structure prices credit, ranks the web, and disciplines how a long-term investor thinks about persistence, reversion, and ruin.

When a question is hard, the mind silently answers an easier one. Kahneman and Frederick called it attribute substitution; for investors it is the swap of “is this a good company?” for “is this a good stock?” — the error that priced the Nifty Fifty and Cisco to ruin.

Born at a sickbed over a game of solitaire and first proven on the ENIAC, the Monte Carlo method replaces the single forecast with the full distribution of what might happen — and teaches the long-term investor to simulate for survival, not the average.

Walter Mischel’s marshmallow test measured a child’s capacity to wait for a larger, later reward — the exact decision the equity market runs on each day. The finding, its honest 2018 qualification, and the disciplines that let long-term investors leave the marshmallow alone.

India measures the same bad loan two ways at once: the RBI’s backward-looking IRAC calendar, which provisions by days past due, and Ind AS 109’s forward-looking expected-credit-loss model, which provisions by what management expects to lose. A practitioner’s guide to the two clocks, the impairment reserve that already bolts them together inside India’s NBFCs, and the April 2027 reform that finally brings the banks under expected credit loss.

For the non-perishable, the longer a thing has lasted the longer it is likely to last. Mandelbrot reversed a 1964 showbiz aphorism; Taleb named it the Lindy effect. What it means for judging a business’s durability — and why most public companies are not Lindy.

Ind AS 115 changed the moment an Indian company is allowed to call a sale a sale: a practitioner’s guide to the five-step, control-based revenue model, the over-time-versus-point-in-time fork that re-wrote real-estate accounting, the new contract assets and liabilities on the balance sheet, the disclosures that reward a careful reader, and why India, the UK and the United States now read revenue from one page.

Nassim Taleb’s Black Swan model holds that rare, high-impact, retrospectively-explained events decide the long run. Why the turkey problem, fat tails and the limits of induction matter more to a long-term equity investor than any forecast.

Rozenblit and Keil (2002) found that the feeling of understanding how things work collapses the moment we must explain the mechanism. From auction-rate securities to Lehman minibonds, the illusion of explanatory depth sells the label and hides the machinery — and three disciplines that puncture it.

For three decades an Indian company could rent a thousand stores or a hundred aircraft and disclose almost none of it on its balance sheet. Ind AS 116 changed that overnight: a practitioner’s guide to the right-of-use asset and lease liability, the front-loaded expense and inflated EBITDA they create, the lessor asymmetry the standard left behind, where India’s balance sheets grew the most, the durable single-model-versus-ASC-842 divergence from US GAAP, and how to read the lease note now.