An Irish software developer believes he has solved James Joyce's notorious near century-old riddle - can you cross Dublin without passing a pub?

Rory McCann, 27, claims he has settled decades of debate about the puzzle in Joyce's masterpiece Ulysses with a simple equation proving it can, indeed, be done.

Using online maps, the Dubliner worked out an algorithm - a computer equation - which found how to criss-cross the capital, from north to south and east to west, away from the temptation of any pub.

"The puzzle was just one of those things I was aware of, like most people in Dublin," he said.

"I started thinking about how you would go about it, the pen and paper route which many people have tried, and which gets very tiring very fast, then I decided to try it on the computer."

The University College Dublin computer science graduate started by plotting out 30 points on either side of the city - 15 along the northside's Royal Canal and 15 along the southside's Grand Canal. The waterways were traditionally regarded as the city limits around Joyce's time.

Mr McCann, from Shankill but now living in Smithfield, then developed his algorithm to try and find a path between a point on the northside to a point on the southside while avoiding pubs marked on the online map website OpenStreetMap.

When he put the riddle-busting route on his website - www.kindle-maps.com - a number of people got in contact immediately pointing out bars which weren't included on the map.

He has corrected it a few times since but is confident he now has the conundrum conquered.

Mr McCann began trying to crack the teaser last year but when he couldn't get it finished for Bloomsday - Ireland's annual June 16 commemoration of Joyce - he put it on the backburner until this year`s event.