No Fixed Points, at Inverleith House in Edinburgh's Royal Botanic Garden, is a curious exhibition. First, John Cage and Merce Cunningham are not well known as visual artists, but as the preeminent composer and choreographer of their generation.

Second, this is not quite an exhibition in the usual sense, but a shifting series of shows, flowing from one dominated by Cage to one dominated by Cunningham.

As the show progresses, Cage's paintings will be replaced by Cunningham's drawings, the timing and sequence of replacement determined by chance: Cunningham rolled dice in response to questions put to him by the staff of Inverleith House, with the numbers rolled corresponding to different works.

This is an eloquent curatorial gambit, one that effectively turns the exhibition into a work in and of itself, and, too, an essay on the closely-linked practices of the two artists.

The show's title is taken from Albert Einstein's maxim that there are no fixed points in space, a phrase that inspired Cunningham to revolutionise his practice as a choreographer, first developing a number of dance phrases, then using tossed coins and cast dice to determine their ordering, the number of repetitions and the placement of dancers on the stage. The technique was refined over time in collaboration with Cage, whose own compositional methods rested on his adaptation of the I Ching, the hugely complex ancient Chinese text that seeks to find order in chance events, offering a set of predictions arranged in a matrix of 64 groupings of six horizontal lines, divined by casting sticks or tossing coins.

It is, too, a problematic approach to displaying work. For one thing, Cunningham is no match for Cage as a visual artist - as he would no doubt admit - so that visitors in late June might find themselves disappointed. For another, the appealing conceptual underpinnings of the exhibition threaten to overwhelm the work it contains, forcing interpretations of works that might not stand elsewhere.

And what of that work? At the time of writing, Cage is firmly to the fore, with just two pieces by Cunningham present in the galleries.

Like much of his music, the two sets of paintings by Cage on show were made according to chance outcomes guided by the I Ching applied to a set of predetermined choices: the colours, the composition and the brushes used. Further removing himself as an artist from the act of creation, Cage also prepared his paper with smoke, and used river rocks as a guide for his brushes. The results, while recognisably variations on a theme, are not the cold, automated, repetitive paintings one might expect. River Rocks and Smoke No 13 is adorned with just two shapes, a yellow square-ish form and a dull brown half-circle, placed low, almost apologetically, on the paper. New River Watercolour Series I, No 3 sees a great horizontal swathe of purple reminiscent of a stave, which looks to have been applied with a housepainter's brush barely troubled with paint, overlaid with a confusion of dull red circles. A trio of paintings from New River Watercolour, Series III - perhaps the best works on show - share a vertiginous downward plummet of dry strokes interrupted by circular forms.

To borrow from the etymology of the characters that form the I Ching's title, these are works that balance simplicity, variability and persistency. They are, too, inherently musical, both visually reminiscent of a graphic score and taut with an internal rhythm.

Cunningham's main contribution at this point in the show's ebb and flow is Blue Studio: Five Segments. At points, it underlines the relationship between the painting composer and the drawing choreographer. In one segment, Cunningham dances a duet with his own outline, in another he performs against a blue screen that slowly fills with shifting white noise, a match for the horizontal washes in Cage's watercolours. In a third, a set of precise hand gestures call to mind a conductor coralling his orchestra.

The single Cunningham drawing present on the day of my visit, Tiger, 5/3/97, is a vibrant little thing - the titular animal has a thick leering tongue and winking eyes, its fur and whiskers a flurry of scratchy marks. And, once again, it is impossible to avoid seeking signs of the artist's primary practice in his drawings, seeing in those hasty marks traces of Cunningham's choreography, of the flickering fingers glimpsed in Blue Studio.

This, then, is a show greater than the sum of its parts, one that, arguably, works better as a conceptual piece in its own right than as an exhibition of works. It is, too, at the risk of sounding sentimental, a moving experience; Cage and Cunningham's long creative association and long partnership continues here, even after the former's death in 1992. In the end, No Fixed Points is an intriguing glimpse at the parallel artistic endeavours of two great artists in other media, and a tribute to the pair's wider, interlocking practice.

No Fixed Points is at Inverleith House, Edinburgh, until July 8. Cunningham's drawings will begin to replace Cage's paintings on June 15.