Pat Lipsky is not merely the dean of contemporary geometric abstraction but its dominatrix. She offers color and shape relationships within structures of unrelenting rigidity, and it is not always clear whether the formal disciplines to which she subjects the eye are for her own satisfaction or the viewer’s. A steely, seemingly dispassionate composure contains seething reserves of aesthetic emotion.

It would be fanciful, however, to detect a range of emotion in her work: Shifts in mood from canvas to canvas are as nuanced as the differences in hue between closely related colors in a single composition. The nine paintings in her fourth solo exhibition with Elizabeth Harris adhere to a strict serial pattern: a pair of thicker columns flank and sandwich three thinner ones, with each column comprising unequal horizontal halves. Color-wise, there are subtly differentiated blacks and reds – the blacks restricted to the thinner columns, the reds free to wander – and shades of blue and gray in more pronounced contrast.

The designs are almost, but significantly not quite, symmetrical. Reductive as her mode may appear, Ms. Lipsky – who began her career in the late 1960s – is no minimalist: More significant than its strictures and exclusions is her painting’s overt, if hard-edged, sensuality. Despite the eggshell, matted finish, her affectless paint delivery makes each bar in the grid pulsate with its own obsessively sought color and context.

The compositions are placed on a ground that forms a framing border: Some are white, others gray. This device inevitably brings to mind Josef Albers and his prim “Homage to the Square” series.

As with Albers, and with Mondrian – as ever the touchstone for all serious geometric abstractionists abstract painters- Ms. Lipsky’s work demands a leap of faith on the viewer’s part. The compositions are placed on a ground that forms a framing border: Some are white, others gray. This device inevitably brings to mind Josef Albers and his prim “Homage to the Square” series. As with Albers, and with Mondrian – as ever the touchstone for serious abstract painters- Ms. Lipsky’s work demands a leap of faith on the viewer’s part. Her formally austere strategy aims to give the viewer a pure color experience . But the actual sensations engendered are divorced from the normal life of the eye, taking the viewer to a conceptual place that’s about color rather than of it.

Even within Ms. Lipsky’s stringent limitations, the recalcitrant eye can never dispel the possibilities of representation. The columns, with their pulsating reds pushing perceptually backwards and forwards, beg to be read also in terms of up and down, like pistons or syringes filling with liquid. The blues, spied around corners in up-down-up or down-up-down sequences, insinuate themselves into sea and sky. They read like organ pipes filling with sound, or the display of a digital equalizer recording its fluctuations.

The more the eye is beaten into form for form’s sake, the more it wanders willfully along paths of association, fantasy, analogy.

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The formal vocabulary of Richard Deacon is simultaneously austere and exuberant. The attitude that comes across in his handling of materials similarly diverges between nonchalance and finesse: A maverick, found-object sensibility cohabits with a virtuoso celebration of craft. Mr. Deacon is at once a maker and a finder.

He is part of a generation of British sculptors, including his friends Tony Cragg and Bill Woodrow, who rose to prominence in the early 1980s. This group was at pains to distance itself from formalism, seeking its antidote in humor, appropriation, and an English spin on the Italian minimal art movement arte povera. Yet Mr. Deacon could rarely suppress a formalist bent.

In one set of works, which remain his trademark despite his diverse output, he arranged sandwiched strips of ply laminate, the glue almost insolently oozing from its layers, into whimsical, open, linear structures. They read like sculptural realizations of Brice Marden’s loops (as Calders can sometimes look like Miros in 3-D). Another American he often resembles is Martin Puryear, who also creates enigmatic forms out of studiedly non-art materials and processes.

Sometimes the collision of found and made is a little too causal for the artist’s own good. “Display Table”(2001) places five readymade sculptural objects, rather like the pebbles and twigs Henry Moore picked up on his rambles, on the pristine, Donald Judd-like display table of the title. This is a forced culture clash, which works rather too hard for the wry smile it at best deserves. Usually, Mr. Deacon is more sophisticated in his style games.

The key to his aesthetic is the way he folds the values of the technologies he appropriates into the sculptural meaning of his work. He is equally open to traditional and industrial-age crafts. The latest works at Marian Goodman take his loop forms to a new pitch of baroque complexity without losing a nuts-and-bolts sense of facture; in fact, he positively revels in it.

The gorgeous, intriguing two-part structure “Red Sea Crossing” (2003) entails multiple twists and convolutions, with steel joined oak strips arching and doubling back on themselves, joined in steel. Forms oscillate between the distressed and the fluent, with a sense of commonplace stuff put to exotic ends. The work brings together the humble and the high, the honest and virtuoso. It is as if Bernini were being helped out by a crew of coopers and wheelwrights.

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To view Richard Deacon and fellow Brit Richard Long on the same Chelsea morning is to savor the distinction between a career that balances radicalism and craft and one that abandoned the latter for the former. Mr. Long, a conceptualist turned would-be shaman, staked his claim to very considerable international attention in the 1970s with a set of iconoclastic gestures that entailed long walks, minimal landscape interventions, precisionist documentation, and rather prissy arrangements of rocks in circles. At his best he taps into forms subtly suggestive of the primordial and the prehistoric.

But the ease and elegance with which he can now fill gallery upon gallery with trite decorations – paintings on plywood with rings of slick handprints and artful dribbles of mud – is a sad object lesson in what happens if the tension between facture and thought is absent. The thinker for whom making was beneath him has become a fabricator for whom thinking is beyond him.