SBC_CONV

reduceLib.SBC_CONV : conv

Calculates by inference the difference of two numerals.

If m and n are numerals (e.g. 0, 1, 2, 3,…), then SBC_CONV "m - n" returns the theorem:

   |- m - n = s

where s is the numeral that denotes the difference of the natural numbers denoted by m and n.

Failure

SBC_CONV tm fails unless tm is of the form "m - n", where m and n are numerals.

Example

#SBC_CONV "25 - 30";;
|- 25 - 30 = 0

#SBC_CONV "200 - 200";;
|- 200 - 200 = 0

#SBC_CONV "60 - 17";;
|- 60 - 17 = 43