The aim of this textbook is to present an account of the theory of computation. After introducing the concept of a model of computation and presenting various examples, the author explores the limitations of effective computation via basic recursion theory. Self-reference and other methods are introduced as fundamental and basic tools for constructing and manipulating algorithms. From there the book considers the complexity of computations and the notion of a complexity measure is introduced. Finally, the book culminates in considering time and space measures and in classifying computable...

Osprey's study of the Battle of Gettysburg (1863), one of the decisive battles of the American Civil War (1861-1865). The Confederate invasion of the Northern states was General Lee's last great gamble. By taking the war to the Union he hoped to force Lincoln into peace negotiations, or win support from the European powers who were watching events closely from across the Atlantic. Equally, Meade's Army of the Potomac needed to regain it's fighting credibility after the setbacks of Fredericksburg and saw this as an opportunity to redeem its honour. The clash of 150,000 soldiers from both sides...

The first major battle in the Western theatre of the American Civil War (1861-1865), Shiloh came as a horrifying shock to both the American public and those in arms. For the first time they had some idea of the terrible price that would be paid for the preservation of the Union. On 6 April 1862 General Albert Sidney Johnston caught Grant and Sherman by surprise and very nearly drove them into the River Tennessee, but was mortally wounded in the process. Somehow Grant and Sherman hung on and the next day managed to drive back the hordes of grey-clad rebels.

Osprey's examination of the Battle of Chancellorsville (1863) of the American Civil War (1861-1865). Following the debacle of the battle of Fredricksburg in December 1862, Burnside was replaced as commander of the Army of the Potomac by General Joseph Hooker. Having reorganised the army and improved morale, he planned an attack that would take his army to Richmond and end the war. Although faced by an army twice his size, the Confederate commander Robert E. Lee split his forces: Jubal Early was left to hold off Sedgwick's Fredericksburg attack, and 'Stonewall' Jackson was sent with 26,000 men...

Osprey's examination of the Battle of Fredericksburg of the American Civil War (1861-1865). In December 1862, things were still confused for the Union. Antietam had been a failure for both sides, and although the battle showed that the Union army could bring the Confederates to bay, it couldn't pin them in one place long enough to destroy them. In December 1862, General Burnside, newly appointed to command the Army of the Potomac, planned to seize and secure the town of Fredericksburg, and then take the Confederate capital of Richmond. Carl Smith's book details the epic struggle that engulfed...

In Sicily, Normandy, and in the frozen hills of the Ardennes, America's airborne warriors proved themselves some of the toughest and most determined soldiers of World War II (1939-1945). What made these soldiers so special? How were they recruited, how did they learn to jump and fight? What special tactics and equipment did they use? This title looks at what it was like to be one of the United States' airborne elite, through the experiences of the soldiers themselves. It is the story of the men who invariably led the way; the soldiers who flew to battle and walked home.