# The Mathematics of Love | Hannah Fry

Summary of: The Mathematics of Love: Patterns, Proofs, and the Search for the Ultimate Equation (TED Books)
By: Hannah Fry

## Introduction

Dive into the world of love and relationships through the eyes of mathematics with Hannah Fry’s ‘The Mathematics of Love: Patterns, Proofs, and the Search for the Ultimate Equation.’ This book summary explores fundamental questions about dating, attractiveness, long-term relationships, and decision-making through a mathematical lens. From Peter Backus’s seemingly hopeless search for love to understanding the role of algorithms in online dating, the summary offers fascinating insights into how math can help us navigate the complex realm of romance. Discover the importance of facial symmetry and the principle of optimal stopping. Embark on this captivating journey as Fry demystifies the mathematics behind love and relationships.

## The Mathematics of Love

Mathematician Peter Backus’s search for love led him to calculate the odds of finding a girlfriend in London. He estimated that out of four million women, just 26 were likely to be a good match for him based on his strict criteria. However, by loosening his standards, he could have had 832 potential partners. This highlights the importance of being flexible in our search for romantic love. Backus’s calculations show that while the odds may seem against us, we can increase our chances of finding love by being open-minded and flexible.

## The Elusiveness of Beauty

The concept of beauty is elusive, and in the eye of the beholder; however, there are underlying mathematical principles connected to beauty. Some suggest that beauty is based on the golden ratio, a mathematical concept applied to human attractiveness. However, the golden ratio theory is flawed as defining precise measurements for features such as the nose, eyes, and ears can be imprecise. Instead, researchers found that overlaying images of numerous faces from a given ethnic group produces an average face shape that is widely considered attractive. This preference for average face shape is believed to be rooted in our evolutionary psychology, where we tend to avoid unusual facial shapes that could indicate genetic mutations. Additionally, facial symmetry is also an important factor that is consistently rated highly in attractiveness surveys. While there might not be a definitive mathematical formula for beauty, these factors play a crucial role in what we perceive as beautiful.

## The Nash Equilibrium

When it comes to approaching someone you’re attracted to, following the Nash Equilibrium is the way to go. This was established by mathematician John Nash, who suggested approaching the four brunettes instead of all the men trying to get the attention of the most beautiful blonde at the party. His theory maintains that it is better to work your way down a list of people you’d like to hook up with instead of making a beeline for the person you find most attractive. If you do the asking, even though there’s a chance of rejection, you’ll end up better off than waiting for people to come to you, resulting in settling for a less preferable person.

## Online Dating: A Brave New World

Dating sites use algorithms to find compatible partners, but there are limitations to how effective they can be.

In today’s digital era, dating sites have become the norm for many to find potential partners. OkCupid, a free site founded by mathematicians, uses a sophisticated algorithm to calculate the compatibility of two individuals. The algorithm generates a score that reflects how well two people match based on their answers to a questionnaire and how important they feel each question is.

For instance, if a user rates a question “Mandatory,” it receives 250 points, and if a question is “Not at all important,” it receives just one point. The algorithm then compares the answers of two people, and the resulting score is an average of their match percentages.

While this algorithm may seem perfect, it still has limitations. The data collected from the questionnaire doesn’t paint a complete picture of an individual, nor does it consider their real-life experiences. For example, two people may both adore the same films, but that doesn’t indicate how they will feel about watching a movie together.

Despite its limitations, dating sites have become a valuable tool for many individuals, especially those who lack the time or confidence to meet people face-to-face. This algorithm may not be perfect, but it does provide a foundation for individuals to build their conversations and relationships upon, as they search for the right partner.

## Mastering the Art of Persuasion through Game Theory

Game theory can help men who want to persuade women to have sex with them by choosing gifts with high value that must be shared to have meaning.

Are there mathematical rules we can use to help us in matters of the heart? Game theory, the study of how people make decisions in situations with multiple participants, can definitely offer some helpful insights. Mathematicians Peter Sozou and Robert Seymour have come up with a creative approach applicable for men who are determined to persuade women to have sex with them. The technique involves assessing a range of available offerings, including flowers or a candlelit dinner, and selecting the most likely gifts to persuade without attracting women who just want the gift. Based on game theory, the woman is viewed as an adversary who uses sex as a bargaining chip, giving you a range of options. Science tells us it’s worth picking gifts of high value that must be shared to have meaning, such as a candlelit dinner, a fancy firework display, or driving a Ferrari to impress your special someone. But stay away from buying jewelry.

The book also highlights that dating can be thought of as an auction, wherein the bidders submit bids. Generally, the strongest bidder, in this case, the most attractive woman, is perceived to have the highest chance of winning the man. However, game theory posits that it’s often the weak bidder who comes out on top. This is because the weak bidder does everything to attract the man’s attention, whereas the confident one is less likely to make the effort. In essence, mastering the art of persuasion involves learning the rules of the game.