J. R. Ellis – författare

Exploring University Mathematics 1 provides information pertinent to pure and applied mathematics. This book discusses a variety of topics, including sets and functions, relativity, integers, waves, isometric problems, and digital computers. Organized into seven chapters, this book begins with an overview of the axiomatic way of introducing natural numbers that is completely satisfactory for mathematical purposes. This text then examines the special theory of relativity, which is a certain kind of geometry of four dimensions that connects three spatial coordinates x, y, z, and a time coordinate t. Other chapters consider the impact that the study of wave phenomena has had on the historical development of mathematics. This book discusses as well the development of the electronic digital computers. The final chapter deals with solving the isoperimetric problem. This book is intended to be suitable for students about to embark upon a degree course of which mathematics is a major part.

A priceless violin. And a dark secret someone is prepared to kill for.Revised edition: This edition of The Quartet Murders includes editorial revisions.DCI Oldroyd has seen his fair share of victims, but he has never witnessed a murder—until now. When world-famous violinist Hans Muller is shot and killed during a concert, the detective is faced with a case beyond logic. The culprit is nowhere to be found—and the victim’s priceless violin has disappeared too.As Oldroyd investigates the mystery of the murderer’s identity and the motive for the killing, he enters the ruthless world of wealthy instrument collectors and stumbles upon a dark path where shocking secrets have been buried in the past. But the secrets will soon take centre stage.Oldroyd must use all his cunning to recover the priceless instrument. But can he also solve the mystery of a murderer who vanished in front of his own eyes?

A murdered crime writer. An idyllic Yorkshire town. Can DCI Oldroyd separate fact from fiction?A famous writer is found murdered at the Victorian baths in the Yorkshire town of Harrogate. In a crime worthy of one of his novels, Damian Penrose, who was appearing at the town’s crime writing festival, has been ruthlessly strangled. But with no trace of the murderer and no apparent means of escape, how did the killer simply vanish from the scene of the crime?There’s only one mind capable of unlocking this mystery: DCI Jim Oldroyd. But as he and his team quickly discover, while Penrose was popular with the reading public, he had made plenty of enemies. Feuds over money, accusations of plagiarism, a string of affairs…His route to the top left a trail of embittered rivals—and suspects. But which of them was willing to commit murder?When Penrose’s shocking death proves to be just the first of many, it becomes clear to Oldroyd that he is dealing with a calculating criminal hell-bent on revenge. He must find and bring them to justice. Before the truth becomes more chilling than fiction…

A murder with three witnesses. But one of them doesn’t believe what she saw…Halloween, Whitby. DCI Jim Oldroyd’s daughter Louise is in town with friends for a goth festival. But their visit to an escape room ends in bloody murder when one of the group stabs his girlfriend and flees the scene. It’s a crime with three witnesses—but Louise refuses to take what she saw at face value.Oldroyd and DS Carter are called in to solve the case, assisted from the sidelines by Louise. But the closer they investigate, the more complex the web of deceit appears. This is no straightforward crime of passion.With a violent murderer on the loose, it’s only a matter of time before they strike again. And this time it’s personal. Oldroyd must expose the truth, protect his daughter and stop the horror before it’s too late.

A puzzling locked-room mystery that puts someone Oldroyd loves in terrible danger…When a film shoot on Wharfedale’s vintage railway turns into a grisly crime scene, DCI Oldroyd’s idyllic visit to the countryside with his partner Deborah is well and truly stopped in its tracks. One of the film’s stars has been shot dead in a train carriage while the cameras rolled outside. But nobody else went in—or came out. Has the killer really pulled off the perfect, impossible crime?Scouring the victim’s past for clues, Oldroyd soon unearths a string of heartbroken lovers and a mountain of unpaid debts, each adding to the growing list of suspects. But before he can determine who the culprit is, there’s the small matter of figuring out how they did it. A potential connection to a previous tragedy offers Oldroyd a much-needed lead…Whoever the perpetrator is, they are ruthless and determined to avoid detection, and when a railway worker starts joining the dots, they are quickly silenced—for good. But as Oldroyd gets ever closer to the truth, it’s only a matter of time before he is given a chilling warning to back off.Perhaps Deborah should have stayed somewhere safe…

An award-winning beer worth killing for. Can DCI Oldroyd find the killer before last orders?Steeped in a history of award-winning Yorkshire ale, the town of Markham boasts not one but two breweries. Richard Foster runs one; his sister, Emily, along with her partner, Janice, runs the other. And not without some resentment.The unwelcome return of the town’s former bad boy, Brendan Scholes, threatens to ignite the sibling rivalry further. Scholes claims to have found the long-lost secret recipe to the beer that made Richard and Emily’s father famous, and he wants money.But it isn’t long before Scholes’ body is found floating in a fermentation tank at one of the breweries, his head caved in by a hammer. DCI Oldroyd and Andy Carter are called in to investigate the murder, and there’s no shortage of suspects.As rumours of the possible existence of a recipe for the famous beer spread against a backdrop of growing homophobia and misogyny, tempers run high. With Markham’s beer industry at stake, a killer on the loose and the town’s residents out for blood, Oldroyd needs to solve the murder before someone else is killed…

Life moves at a slower pace on the canals. But death always comes when you least expect it.The last thing DS Stephanie Johnson and DS Andy Carter expected during their much-needed canal holiday was a murder. When retired folk musician Annie Shipton is found stabbed through the neck at the helm of her barge, the couple can’t help investigating the seemingly impossible crime. Nobody else boarded Annie’s boat—so how was she killed from behind?With the method a perplexing mystery, DCI Oldroyd is summoned from Harrogate, and it’s not long before the detectives have a long list of potential suspects with a motive to want Annie dead. There’s the young cyclist she argued with over access to the towpath, an ambitious and arrogant local developer she clashed with repeatedly, an estranged husband…and more than a few lingering issues with her former bandmates, most of whom live along the canal.When a second murder sends shockwaves through the community, the locals start talking about a curse on the waterway. It seems the killer will go to any lengths to avoid detection. But can Oldroyd hunt them down before someone else becomes the next target?

He was supposed to be gone forever. Now he’s back.Ten years ago, DCI Oldroyd was the only person who could see the monster hiding behind Adam Blake’s charm. Oldroyd proved that Blake was a deadly serial killer, responsible for murdering many innocent people. Having vowed to take revenge on Oldroyd, on a crisp autumn morning Blake escapes from jail…Hours later, in the Yorkshire market town of Otley, a man is found strangled inside the old courthouse. Written in bold black ink across the victim’s forehead is a single chilling word: vindicta—revenge. Oldroyd’s blood runs cold when he picks up a call and hears an all-too-familiar voice: I’m coming for you.Oldroyd has spent years getting inside the minds of dangerous murderers to protect lives. But with a determined killer closing in, can he catch Blake once more and solve this difficult case, or will Oldroyd be the next to die?

A murder in a locked garden. A village full of secrets. Can DCI Oldroyd find a killer who has vanished into thin air?When a woman is found strangled in the locked garden of historic Bishop Hewick Hall in Yorkshire, DCI Jim Oldroyd needs to solve a seemingly impossible murder. The only door was bolted from the inside and the kitchen garden walls are too high to climb. If no one could enter or leave, how did the killer commit the crime and escape?As Oldroyd and his team investigate the victim’s past, they discover Clarissa Morden wasn’t the kind elderly woman she appeared. Instead, she was a ruthless blackmailer who kept coded records of her neighbours’ darkest secrets. Her list included a local cabinet maker, the Bishop Hewick Hall manager and even her next-door neighbour—suddenly it seems as if half the village has a motive for murder.When a second body is discovered in the local river, it seems this quiet corner of Yorkshire may never be the same again. Can Oldroyd unlock the secret of the impossible locked garden murder and find the culprit? Or will the killer strike again in this tranquil village to keep their secrets hidden…© 2026 by J. R. Ellis, all rights reserved.