The question of how one defines and delimits a work of art is neither new nor in danger of resolution. This year, Frieze's sculpture park (which closed yesterday) offered a wide range of work with seemingly little in common in media in theme, but for a recurring inquiry as to the role and impact of the viewer as an active agent addressing each piece. Situated in Regent's Park's rambling but manicured English Gardens, minutes  from the fair, it by consequence of it location occupies a dual position: an annual index to the significance of monuments, and supplement to Frieze's branding.






Fittingly, Gavin Turk's contribution, Les Bikes du Bois Rond (2010) (Frenglish for "The Bikes of the Round Woods"), consisted of 15 colorfully painted Dutch bikes, simultaneously echoing leisure activities and André Cadere's multicolored sticks. One rented these out and ride in the inner circle of the park, and would receive a certificate signed by the artist authenticating the experience as a work of art—referencing Piero Manzoni, who, in the late 50s signed people and awarded them certificates of authenticity, and tying it to Tino Sehgal's contemporary exchange of performances. Turk borrowed the format of a tourist activity, but holds a mirror to the viewer.

An opposite approach, yet with a similar frame of interrogation was Jeppe Hein's 1-Dimensional Mirror Mobile (2009). Consisting of a flat, round mirror hanging from a tree, the work at first seemed to suggest that the viewer's reflection was to become part of the piece, on each approach creating a unique image. Yet the mirror, hung by two metal cords, one from a tree and the other from the ground, spun rapidly without ever focusing on the exterior, thus losing its reflective accuracy. The technique was typical of Hein's work, who often confuses or deflates the active involvement of the viewer: in his 2003 piece, No Presence, a globe filled with neon lights and sensor switches lit once the viewer walked away from the art piece.

Sanchayan Gosh's DOOSRA—The Other Maze (2010) included a maze of bamboo sticks filled with white roses to spell out the word Doosra, which meaning "Other" in Hindi-Urdu and is commonly used as in cricket. Upon entering the game, a note encouraged viewers to pick out a flower, allowing each to walk out with a piece of the artwork—or more frequently, an entire bouquet. The participants' greedy reaction to free yield was a highlight, intentional or not.

The main difference between the Sculpture Park and the fair itself, is that the former is free. By nature of its location, public sculpture performs a decorative function opening onto the fair, echoing Tony Cragg's sculptures on London's Exhibition Road, pathing the way to the Victoria and Alberts Museum.