Paris designer Pierre Cardin has a solution for the woman who can't make up her mind about short skirts. At the kickoff showing of spring haute couture designs in Paris this week, Cardin showed skirts with hemlines sliced asymmetrically to be short on one side and long on the other, and short skirts with long side panels for a similar effect to appease the undecided.

Cardin's hemlines made about as much sense as another fashion introduced at the house of the late Elsa Schiaparelli - the $15 million dress. Undeniably the most expensive dress ever made - the closet, perhaps, being Yves Saint Laurent's sable-trimmed peasant costumes with $9,000 price tags of a season ago - the Serge Lepage design is studded with 512 diamonds totaling 650 carats.

The French Communist Party daily L'Humanite figured that it would take a skilled worker 350 years to buy the dress. The model was transported in an armered-plated van with armed guards for the showing.

More important for American women is the return of Dior prints. Designer Marc Bohan likes florals, but he also uses soft geometrics in his billowy silhouettes. It may just bring back printed dresses, which American women have always liked but haven't worn in a long time.

Important to watch, too, will be the entrance of Hanae Mori, a Japanese-born designer who has opened a house on the Avenue Montaigne. Mori is a master of prints and handpainting, particularly appealing in silk chiffon.

The Lepage design was part of a small collection shown by the Schiaparelli house to get attention for new perfumes the house will introduce soon. The collection, the first shown at the house since 1955, is likely to be a one-shot effort for publicity purposes according to La Marquise de Coccupuoti, daughter of Schiaparelli and mother of cover girl-film star Marisa Berenson.

The Yves Saint Laurent wasp-waisted, full-skirted designs of the last two seasons are expected to bn a major theme at this week's showings. Also expected are several versions of the above-the-knee hemline, always offered as an alternative to longer lengths.