It's well known that artists are shameless self-mythologisers, but even so Max Ernst's account of his beginnings is pretty much out on its own. He first contact with the world came, he wrote in a brief autobiographical sketch in 1961, "when he emerged from the egg which his mother had laid in an eagle's nest and which the bird had incubated for seven years. This took place at Bruhl, six German miles south of Cologne. Here Max grew into a beautiful child."

It may sound like a piece of magic-realist whimsy, but his account of his life from his birth in 1891 to what he describes as his rebirth after the war in 1918 (he died in 1976) is packed with unlikely sounding detail that offers genuine insight into his remarkably various work. Memories of his early years, including a trip into the forest with his father and two deaths, that of his sister and "one of his best friends", a pink cockatoo, provided a fund of imagery that he drew on throughout his life.

An outstanding exhibition of his graphics, plus a few paintings, at the University of Limerick's Bourn Vincent Gallery offers a rare opportunity to see a representative selection of his output, drawn from the extensive collection of the Wurth Group in Germany.

The word "graphics" in relation to many artists means peripheral, but not for Ernst. His most original work often took graphic form. His pictorial novels, for example, cannibalise 19th century engravings and recast them as surrealist collages. But it is as if the stuff of the unconsciousness, repressed desires, perversion, terror, irrationality, have spilled uncontrollably out and subverted the strait-laced Victorian facade.

Ernst's images, with their human-animal-machine hybrids, are eerily atmospheric and evoke a half-familiar but disorientating dream-world. His fellow Dadaist, Hans Richter, perceptively pointed out that he brought a German romantic sensibility to Dada.

Ernst didn't invent collage, but he used it with great originality. He is generally regarded as having reinvented another art form familiar to virtually everyone: frottage - that is, making an image by putting a sheet of paper against a textured surface and recording its impression with black lead or some other medium.

A charming man who was universally liked, he was a brilliant, unconventional spirit. Early on, he had abandoned philosophical studies in favour of painting and was instinctively drawn to avant garde movements. Appalled by his experiences - a mixture of boredom and horror, as he put it - serving as an artillery officer during the first World War, he became involved with the Dada movement, but he was always less political than many of his fellow artists of the time.

He moved to Paris in 1922 and felt completely at home, so much so that a friend later remarked that if Paris hadn't existed, "it would have had to be built specially for him." After the birth of surrealism in 1924 he became identified as a Surrealist, but the labels are not that significant. He was predominantly a quirky, independent thinker, and there is no break between the work of his Dadaist and Surrealist phases.

He is a very cerebral artist, which accounts for both the strengths and limitations of his work. On the one hand there is the rigorous, incisive intelligence with which he follows up ideas and possibilities. On the other the analytical self-consciousness that prevents him from abandoning himself to an idea or a possibility. So that, to take one well-known example, when he dripped paint to make an image in 1942, the results look hopelessly tight and constrained by comparison with the efforts of the artist whose technique he anticipated: Jackson Pollock.

Mike Nelson's Tourist Hotel, at the Douglas Hyde Gallery, prefaces an ambitious architectural installation with a series of architect's drawings. These plans, apparently for a vast hotel complex, blend various cultural references so that we're unsure of location and identity - though one gets a sense of the crude cross-cultural grafting that characterises, for example, some expensive Middle-Eastern developments. With pointed incongruity, the modestly scaled drawings are arranged in the gallery's huge central exhibition space, consigning the main part of the show to the recesses of the gallery, as though it's an afterthought.

Walk through a plain padlocked door and you are transported from the big, rather brutalist gallery to the interior of a pokey North African or Middle Eastern hotel. It would be unfair to describe it in detail, for much of its effectiveness depends on the theatrical ingenuity with which the environment is contrived. Make your way through the warren of spaces and you will eventually find that it all ends in a very bad trip indeed - or is it a nightmare of global capitalism? It's an effective denouement, but the best part of Tourist Hotel is the "hotel", surreally insinuated into the modernist architectural framework in a way that would, you feel, have appealed to Max Ernst himself.

On the face of it there is undeniably a violent element to the dominant image of Cathy Carman's sculptures at the Temple Bar Gallery. Fish heads push through a female torso in a way that recalls the nasty extraterrestrial creature in the original Alien. Yet the show is actually very gentle in feeling, and not only in comparison with much of her previous work, whether in wood, stone or bronze. There was often a sense of aggression and frustration in the way she hacked into her rough-hewn figures.

Perhaps the fish imagery has something to do with Jungian psychology, in which fresh and seawater are the realms of intuition and the emotions, and fish are powerful symbols, representative of the unconscious. The title of her show, Homage to My Mother couldn't be clearer. The work, she elaborates, is a way of remembering her mother, who died in 1993.

She has made a series of plaster torsos that are extremely sensitive, even delicate in feeling. Instead of the heavy masses of her carved work, these are light, almost ethereal objects, fragmentary and hollow, but they also express tremendous physicality. They are vivid expressions of memory, transience and absence.

Max Ernst: Graphic Works is at the Bourn Vincent Gallery in the University of Limerick until March 26th. Mike Nelson: Tourist Hotel is at the Douglas Hyde Gallery until March 27th. Cathy Carman: Homage to My Mother is at the Temple Bar Gallery until March 12th.