getBitstrings function

Bitstring Representation of a Spread or Star

This function computes a bitstring representation for a spread or star of PG(n-1,2)

getBitstrings(spr)

Arguments

• spr: A spread or star of PG(n-1,2) stored as a three dimensional binary array (see Details and Examples of checkSpreadEquivalence).

Details

This code obtains the bitstring representation (as described in Spencer et al. 2019) for any given spread or star of PG(n-1,2). The spread should be formatted as a 3-dimensional array with spr[i,j,k] indicating whether or not the ith basic factor is present in the jth effect of the kth flat of spr. This representation facilitates fast equivalence checking for spreads or stars.

Returns

A matrix with each row characterizing the elements of a distinct flat in spr.

References

Spencer, N.A., Ranjan, P., and Mendivil, F., (2019), "Isomorphism Check for $2^n$ Factorial Designs with Randomization Restrictions", Journal of Statistical Theory and Practice, 13(60),1-24 [https://doi.org/10.1007/s42519-019-0064-5]

See Also

checkSpreadEquivalence for checking equivalence of spreads.

checkStarEquivalence for checking equivalence of spreads.

Author(s)

Neil Spencer, Pritam Ranjan, Franklin Mendivil

Examples

## Example 1: The bitstring representation of a 1-spread of PG(3,2)
data(spreadn4t2a)
getBitstrings(spreadn4t2a)


## Example 2: The bitstring representation of a star of PG(4,2) consisting of 4-flats.
data(starn5t3a)
getBitstrings(starn5t3a)